I'll play for Enterprise:
1. The fans. We're incredibly international (Roddenberry would be proud) and diverse, we're supportive, we're not afraid to debate, we're (in the case of Enterprise) sometimes the underdogs, we're fun and a little bit goofy. We have great taste in television, books, and fanfiction

You don't see that in a lot of fandoms.
2. The Xindi arc. They attacked Earth and carved up Florida (sorry Floridians). Ignoring the lame calling card point of the attack, it was awesome. It hit home, literally, and gave new life to the series.
3. The characters are like us-- they act like we would in the same situations. Instead of the far-removed-from-modern-humanity's "oh, space is so blase, I do this every day" attitude of the "later" Treks, the Enterprise crew finds everything so interesting... Trip and his camera had the touristy moment, there's still Xenophobia on Earth, and, like someone said, it's so easy to picture our grandchildren on Enterprise. They're human and relatable.
4. Of course, Trip and T'Pol. A real, nuanced relationship. Too bad some of the writers (and BnB) had a habit of screwing it up...
5. I babbled on about this at the Cherry Hill con, but they finally had a relatable (and hot) engineer. I belong to one of the uncoolest professions (there's no TV show about engineers-- we've got lawyers and doctors and cops and marketing people, but no one wants to see an engineer in action) Sorry to say about the other Treks, but: A. Scotty-- relatable (although TOS is from so long ago that he still fit something of the "old school" engineering stereotype. But for his time, he was very relatable), but not hot. B. Geordi. Wore a headband on his face. Never got the girl. His best friend was a robot. See my point? C. Miles O'Brien. Boring. But he had a cute kid. Honestly, how many people out there would say, "I want to be cool and be an engineer like O'Brien"? D. B'Elanna. I loved her character, but, sorry, she made us female engineers come across as b*tches. We can already get labeled as such, since we have to be tough in a male dominated environment, but I would think that by the 24th century, there wouldn't be that attitude. Yes, she was half Klingon, but all I saw was a female engineer who had to be tough and sometimes nasty to be good. And, finally: E. Trip. Normal. Guy-next-door with the normal girl trouble and hobbies and family. Brilliant but not an ass about it. Loyal, accident prone, shares a beer with his boss. Relatable. And hot. He's actually cool enough that I can see him inspiring people to go into engineering.
6. Seeing the birth of all of the Trek technology. I love their fear of the transporter, and how Hoshi felt about the ship jumping to warp in the beginning. (ooh,and the moment in Broken Bow when Malcolm pulls out the case with the new phase pistols and they all salivate over the cool new weapon)
7. Malcolm's motion sickness. As someone who gets incredibly motion sick at the slightest thing, it was nice to see that people of my ilk are even represented in space
8. Phlox. I love phlox. Phlox Rocks.
9. There are zippers on their uniforms. No offense to Gene Roddenberry, but stating that we eliminate all zippers and buttons and the like by the future is kind-of lame. I like zippers.
10. "They put the Ho back in Hoshi"

and the rest of the MU romp