Interesting question. There's a lot to factor in when deciding a rank for each era... how good were the stories, how was the franchise run, nostalgia, other things. I'm going to go from worst to best.
5. Abrams era - While I will credit his first movie with reigniting interest in the franchise, there's not much else I can say about it. And the second movie was just plain terrible. BEYOND, which was not even his movie, was FAR superior to both his movies... combined. So one good movie out of three, which comprised his entire era? No surprise why I rank this as the worst.
4. Kurtzman era - This was actually tricky for me... I was unsure if I would rate this 3rd or 4th place. The positive thing about the Kurtzman era is that there is truly something for nearly every type of fan. You want humor? Tune in to LOWER DECKS. You want to see legacy characters have one last shining moment under the sun? PICARD is ready for you. You want something your kids can enjoy? (And let's be real, the adults too... much to my surprise.) PRODIGY warps into your tv screen. You want a really serialized show, year after year? DISCO and PICARD. You want a return to an era of one and done episodes? STRANGE NEW WORLDS are ready to be explored by you. The spirit of STAR TREK is definitely in all these shows, with the exception of PICARD... but that's a conscious decision in tone. The negative about this era? The heavily serialized shows really struggle to stick the landing... so much so, that only the most recent DISCO 4th season ending did it, and PICARD season 2 mostly did. The middle parts of all their seasons are so... dragged out. It brings it all down. Only SNW and the animated shows are firing on all cylinders with mimimal issues. And since that is barely half the amount of episodes, I am forced to put this era in 4th place. Plus, the era is still ongoing, so I can't look at it backward quite yet.
3. Bennett era - Harve Bennett gets credit for breathing life back into the franchise, and it's well deserved. TWOK is still the gold standard of the movies, which has still yet to be matched 4 decades later. And while some of the stories or plots on some films are questionable at best, the one thing all movies have in common is great character beats and interactions. And characters are ultimately why we watch anything.
2. Roddenberry era - It's the era that started it all, so it was going to end up in either of the two top spots. We have TOS, which has a lot of good episodes and many classics. And we have early TNG, which despite some misfires, brought a lot to the table. And ultimately, my nostalgia kicked in because TNG is the reason I became a science fiction fan, particularly due to Data. There are some wonderful clsssics here, too, with "Where No One Has Gone Before", "Home Soil", "The Arsenal of Freedom", "Where Silence Has Lease", "The Measure Of A Man", "Q Who", "Yesterday's Enterprise", "The Offspring", and "The Best of Both Worlds". Season 2 of TNG really made space feel dangerous again, a feeling we rarely got later on.
1. Berman era - While many will call this era 'comfort food', and that may be true, there were a LOT of great episodes here: "Darmok", "Ensign Ro", "Ethics", "The Outcast", "The First Duty", "I Borg", "The Inner Light", "Relics", "Schisms", "Chain Of Command", "Frame of Mind", "Parallels", "The Pegasus", "Lower Decks", "All Good Things...', "DUET", "NECESSARY EVIL", "BLOOD OATH", "THE WIRE", "CIVIL DEFENSE", "IMPROBABLE CAUSE"/"THE DIE IS CAST", "EXPLORERS", "THE WAY OF THE WARRIOR", "THE VISITOR", "SONS OF MOGH", "HARD TIME", "THE SHIP", "TRIALS AND TRIBBLE-ATIONS", "FOR THE UNIFORM", "IN PURGATORY'S SHADOW"/"BY INFERNO'S LIGHT", "IN THE CARDS", "CALL TO ARMS", the 6 part Occupation arc, "THE MAGNIFICENT FERENGI", "FAR BEYOND THE STARS", "IN THE PALE MOONLIGHT", "TREACHERY, FAITH AND THE GREAT RIVER", "ONCE MORE UNTO THE BREACH", "THE SIEGE OF AR-558", "COVENANT", "IT'S ONLY A PAPER MOON", "TACKING INTO THE WIND", "WHAT YOU LEAVE BEHIND", "EYE OF THE NEEDLE", "HEROES AND DEMONS", "JETREL", "PROJECTIONS", "MANEUVERS", "DEATH WISH", "MELD", "DEADLOCK", "THE THAW", "TUVIX", "DISTANT ORIGIN", "WORST CASE SCENARIO", "SCORPION", "NEMESIS", "YEAR OF HELL", "MORTAL COIL", "MESSAGE IN A BOTTLE", "PREY", "LIVING WITNESS", "NOTHING HUMAN", "TIMELESS", "COURSE: OBLIVION", "THINK TANK", "SOMEONE TO WATCH OVER ME", "SURVIVAL INSTINCT", "TINKER TENOR DOCTOR SPY", "ONE SMALL STEP", "BLINK OF AN EYE", "MEMORIAL", "IMPERFECTION", "DEAR DOCTOR", "VOX SOLA", "MINEFIELD", "DEAD STOP", "COGENITOR", "TWILIGHT", "SIMILITUDE", "PROVING GROUND", "AZATI PRIME", "DAMAGE", "THE FORGOTTEN", the Augments trilogy, the Vulcan trilogy, "OBSERVER EFFECT", "UNITED", "IN A MIRROR, DARKLY". You have the pilots of DS9, VGR, and ENT all being great ones. And while Rick Berman may have stayed at the helm for a bit too long, he DID keep STAR TREK on the air for 18 straight years. No other genre franchise can say that. (And it's extremely rare outside the genre, too. I think NCIS might be the only exception.)
The one thing that gives the Berman era the top spot is DEEP SPACE NINE. I feel a deeper connection with this show than any of the others because it was a place where even the outcasts of a society were welcome. You had excellent characters with a stellar cast. You had wonderful writers who never insulted your intelligence. DS9 has aged the best out of any show. But the reason why DS9 is the hightlight? It's the show that is truest to the spirit of the franchise. You have two completely different philosophies running the station. (Starfleet and Bajoran) You have a civilian population that also has different values. (Quark) You have science and religion, with good points and bad for both... and never once was the audience told one way was better than the other. You have half the cast being outcasts of their own culture (at one time or another: Worf, Odo, Quark, Garak) being welcome there and working together. What better message is there than, 'You may not belong or be welcome by your own people, but you are welcome here'? THAT is the best message you can give, and DS9 best exemplifies that message. Hell, I can give you an exact scene that says it more clearly than I could... the last few minutes of "BODY PARTS", when everyone on the station comes to help get Quark back on his feet after the FCA takes away all he has.
I honestly did not expect this post to be as long as it was (this may very well be the longest post I have ever written), but I thought I should be fairly clear on why I ranked the eras the way I did.