%90 of the comics made are shit and %90 of the people reading comics have bad taste.
This isn't the language I'd have used, but it's entirely true. Most comic books produced, even by the major publishers, are terrible.
Green Lantern - There's a huge space war going on which is just too big to explain and wonderful to drown in that's been building to a boil for the last three years.
Green Lantern has some flaws (notably sometimes poor artwork in Green Lantern Corps, the auxiliary series, as well as writing that could be slightly better), but has been very strong for the last few years. I recommend the trades for this series. You might want the Green Lantern Corps trades as well, or you could start with the excellent Sinestro Corps War crossover, which was structured to be able to work as a jumping-on point.
Booster Gold - Kooky time travel fun. There's a guy in it called Supernova.
What I've read of this has been decent, but not spectacular.
Ex Machina, The Boys, and Lost Girls, are all too weird, disturbed, or depraved for me.
Detective Comics - This is the best bat-title out there at the moment being written mostly by the bloke that used to be in charge of the animated toon in the 90s.
The art on this is often poor, but the writing has been generally decent, with some truly outstanding installments. My favorite issue is a Joker/Robin Christmas story that's not at all sweet, but an excellent traditional Batman tale nonetheless. There are also nice stories featuring the Riddler, Zatanna, and a local magician.
Planetary - best comic series ever. Well maybe with the exception of the Authority, but that was written by the same guy and they crossed over all the time. Archeologists researching the secret history of the 20thcentury where in every conspiracy theory urban legend pulp story and comic book actually happened but it was hushed up by the evil bastards in charge.
Planetary is indeed excellent. The more you know of the history of 20th Century popular science fiction and science fantasy (to a point, I'm sure), the better the series reads. I'm sure it reads brilliantly if you have just a basic familiarity, too. The story of the Planetary organization begins as something that doesn't seem especially notable, but it is magnificent by the end (well, the near-end; the final issue hasn't been released).
My top recommendations:
The Ultimates (available in trade paperback as The Ultimates vols 1 & 2 or in hardcover as The Ultimates)This is the very slick and well-done story of Marvel's Avengers (Captain America, Iron Man, Thor, Giant Man, the Hulk, and the Wasp) as begun in the modern world, not the 1960s. It's one of the best comics ever published.
The Ultimates 2 (available in trade paperback as The Ultimates 2 vols 1 & 2 or in hardcover as The Ultimates 2) The outstanding continuation of The Ultimates. While at first it might seem inferior to the original volume(s), this series is a worthy successor, which delivers one of the best endings I've ever seen.
Kingdom Come (available in trade paperback or as a giant 'Absolute'-sized hardcover) A brilliant story of a world in which Superman left heroism to another generation, only to find that it became a world without heroes. This was the first American comic my college-aged friends ever read, and they both loved it. One enough that she wanted to read more every time she visited, the other enough to seek out X-Men comics on her own (she was a fan of the X-Men movies). It's a truly terrific story, with excellent painted artwork.
The World's Greatest Super-Heroes (available as a giant 'Absolute'-sized hardcover or in constituent tabloid-sized trade paperbacks) This is the collected version of a series of smaller volumes starring several of DC's most notable heroes. Each story highlights a key aspect of Superman, Wonder Woman, Captain Marvel, or the Justice League. My favorite is SHAZAM: The Power of Hope, featuring Captain Marvel and his alter-ego, young Billy Batson. Even my sister, who hates the title's generally esteemed painted artwork, loved the tale.
Batman: Hush (available in trade paperback as Batman:Hush vols 1 & 2 or in an 'Absolute'-sized hardcover as Absolute Batman: Hush) A terrific story of Batman facing off against the bulk of his rogues' gallery, centered on a murder mystery involving the death of one of Bruce Wayne's childhood friends. This features very polished art by the justly popular illustrator Jim Lee, who famously redesigned the X-Men in the early 1990s.
Impulse (not currently available in trade, or in new issues) A charming series about a kid speedster from the future (the grandson of the 1960s Flash) who is woefully out of place in a modern (and non-virtual) world. It's goofy at times, but is great fun and full of heart. I'd ignored many recommendations on its behalf before I read it, and almost regretted not having read it sooner (almost, only because leaving it to read meant it was longer until I'd run out of issues).
Wonder Woman Vols 1-5 (available in trade paperback) Writer-illustrator George Perez's 1980s relaunch of Wonder Woman was fantastically conceived, and made only a few missteps (though a few, notably the changes to Steve Trevor, Etta Candy, and Wonder Woman's secret identity, later crippled the series). Steeped in Greek myth and rendered in detailed and skillful illustrations, these stories are must-reads for anyone with even a passing interest in the Amazon hero. The stories The Aries Affair and Challenge of the Gods are especially noteworthy.
X-Men: The Dark Phoenix Saga (available in trade paperback) The comic book classic which nearly invented the modern comic 'saga.' This is the story of the rise of the Phoenix, and the inexorable destruction of the young woman named Jean Grey. Though slightly dated, this is still one of the greatest comic stories ever penned.
All Star Superman (available in hardcover or trade paperback as All Star Superman vols 1-2) An immortal story of the last days of Superman, his twelve labors, and his final confrontation with the mad genius Lex Luthor. Slow to start, illustrated with artwork that oscillates from the beautiful to the grotesque, this is a magnificent testimony to all the reasons Superman has inspired in his seventy years on the page.
Also worth a Look:
Planetary (available in hardcover as Planetary vols 1-4 or in giant 'Absolute'-sized hardcovers as Absolute Planetary vols 1-2) This is the story of the secret history of the 20th Century, and of a man who finds himself pulled into the middle of it. Elijah Snow and the Planetary Organization seek to uncover the great secret of the century, before the secret catches them.
Avengers Forever (available in trade paperback) The defining story of Marvel's Avengers. This series is steeped in Avengers lore, but is accessible and exciting for an Avengers initiate. I had never so much as seen an Avengers comic before reading this, and loved it. Avengers Forever is an unexpected epic which is unusually clear. (I later learned the series was meant to clean up Avengers history while telling a quality story.)
Superman: Red Son (available in trade paperback) An outstanding tale of a parallel world. What if Superman were not the champion of the American way, but the greatest hero of the Soviet Union. Produced in 2003, this series is not a Cold War relic, but a classic tale of the Man of Steel. Occasionally hampered by poor artwork, the series is nonetheless carried into the realm of classics by its engaging, arresting tale. You'll remember this one.
Ultimate Fantastic Four Vols 5-6 (available in trade paperback, or in hardcover as Ultimate Fantastic Four vol 3) The Fantastic Four reenvisioned by the writer of the Ultimates. I couldn't do these stories justice with an explanation, but suffice to say that Crossover, President Thor, and Frightful are three excellent, memorable stories. If you enjoy these, try vols 1-4, which are also relatively worthwhile.
The Legion of Superheroes Vols 1-5 (available in trade paperback) The clever reimagining of one of DC's hero franchises. Carried off with apolmb and skill, this series succeeds in bringing science fiction to comics as hasn't otherwise been done in modern times. Well-drawn characters, interesting plots, and clever twists drive the series, which is hampered slightly by an only occasionally-showing bizarre love of comic books in the 31st Century world of the Legion. The fast, smart comics is more descended from our world than it is the usual DC universe. The title briefly changed to Supergirl and the Legion of Superheroes for the later volumes. The relevant volumes are written by Mark Waid and illustrated by Barry Kitson, should the title confuse.
Astonishing X-Men (available in trade paperback as Astonishing X-Men vols 1-4 or in hardcover as Astonishing X-Men vols 1-2) Written by Joss Whedon of Buffy the Vampire Slayer, Angel, and Firefly name, this is a generally competently-executed recent modern take on the X-Men. The story is slightly thin in parts, and there is a retroatcive continuity element which doesn't sit well, but at least two of the four volumes, Gifted and Unstoppable, are spectacularly executed. This is a story best read as a whole.
X-23: Target X (available in trade paperback) Ignore the premise of this title. It's nothing like you'd think it would be. X-23 is a clone, a weapon created from a partial DNA sample taken from the X-Men's Wolverine. This is the captivating, moving story of her escape from her captors - her creators - and her search for a home and a purpose in a world where she has a chance to live the life of a child, not as the world's deadliest weapon. Rendered with beautiful, dynamic artwork and a mesmerizing story, this will surprise you. It's one of the best.
Green Lantern (available in hardcover and sometimes trade paperback in Green Lantern: Rebirth, Green Lantern vols 1-3, Green Lantern: The Sinestro Corps War vols 1 & 2, Green Lantern: Tales of the Sinestro Corps, and Green Lantern: Secret Origin) This is the story of Hal Jordan, test pilot and officer of the interstellar Green Lantern Corps. Relaunched a few years ago, the series is in mostly capable hands, and has only improved with each year under the belt of this new direction. If you like current superhero comics, Green Lantern is a good bet. It does what others do, but best.
Accompanied by a companion series, Green Lantern Corps (available in trade paperback as Green Lantern Corps: Recharge, Green Lantern Corps: To Be A Lantern, Green Lantern Corps: A Darker Side of Green, and Green Lantern Corps: Ring Quest).