For my money, Enterprise got "good" from the very start. Aspects of the show criticized so often like Archer's uncertainties and Phlox' quirks made the show entertaining. The evolution of the Human / Vulcan / Andorian relationships intrigued me throughout, especially as reflected in Archer / T'Pol. Enterprise remains my second favorite Trek series, just a hair behind TNG and might have taken over the top spot had it continued,
I'll let you in on a little secret, OP. It doesn't.
It's good from the beginning.
These.
I'm one of the happy little band who loves Archer - his foibles, his screwups, his stumbling his way to maturity and greatness. I think he was doing the best he could within the bounds of his awareness, and his horizons were widened as he went along - especially by the war. He was the first of his kind, and as was said upthread, he was the one to write the first textbook on how to be a starship captain. He learned the hard way, but he learned. To watch his eager idealism in the beginning, then see his disillusionment, his moral struggles during the war, and finally his emergence in Season 4 as a better captain and budding diplomat, was just marvelous for me. I love that he was Kirk's hero and role model, but he was just a man, imperfect, but a true trailblazer.
I'm also right in the front row to protest how inconsistently the character was written. The writers didn't take good enough care of him, and considering he was the captain, that's a shame. But when I set aside the dopey character inconsistencies and focused on Archer's strengths - his humanity and kindness, courage and selflessness, his unassuming heroism, and especially his ability to learn from his mistakes, I just fell in love with him.
I really appreciated how Archer and T'Pol were used as a microcosm for the humans and Vulcans learning to put up with each other and finally unite as solid, trusting allies. They both had huge flaws in the pilot, and we watched them grow, go from open dislike to wariness to trust to deep friendship, and I loved that. I loved how Archer recognized T'Pol's worth and fought to keep her on
Enterprise from the first season onward. I thought their evolving relationship was one of the best elements of the show.
I loved the character interaction on this show. Every episode, no matter what I might have thought of the plot, had some great character bits. From Archer and Trip sharing a beer and a polo match to Hoshi teaching Archer how to insult like a Tellarite to Porthos comforting Archer as he looked over the rosters of the victims from "Shockwave," there were wonderful moments. And it had Shran and Soval, what's not to love about them? In any scene they were in? Gold, just gold. I would have loved to see more Archer/Shran and Archer/Soval in the 3 seasons we didn't get.
The show even had Trip and T'Pol as a microcosm for human/Vulcan relationships, which could have been a precursor for Sarek and Amanda. Sure, fits and starts, but overall there was a lot of promise there, good groundwork laid in Season 3, but the whole thing got derailed in Season 4 because of the impending cancellation, and then the stupid "we broke up" nonsense in the final waste-of-an-hour, which was just inexcusable, story-wise. Don't get me started, I already wrote enough fanfic about it, lol. Missed opportunity, sad.
I watched the first 3 seasons all in one go over a month, before Season 4 started, without yet joining any online communities or being exposed to all the criticism and fanwars and all that. I just sat and watched and loved it, because it was new Star Trek, and it was Bakula, and the production values were terrific, and I wanted to love it, and I really did. I forgave it its flaws and just enjoyed the hell out of it. I could easily have watched it for 3 more seasons. I will always feel cheated that it didn't get to do that.
TOS will always be my first love, it was my introduction to sci-fi and helped to form my worldview. But
Enterprise is the show I have the most passion for.