Digimon Tamers was my favorite

Nostalgia : Adventure.
Best plot : Tamers.
Best reconstruction : Xros.
Killed the series : Data Squad, Frontier.
Only good as a sequel : Adventure 02, Xros Wars 2.

Adventure
Adventure 2
Tamers.

All I've seen, though.

I think Season 3 (Tamers) had the best characters and story, it also had the worst animation.

My favourite one is Tamers. I like Adventure and Adventure 02 for nostalgia reasons.
Tamers imo had the best atmosphere, characters and story. It even dealt with some really adult themes and steered Digimon away from the monster of the day formula to having a deep overarching story.

Frontier was ok, but somehow I didn't like it as much.

Savers/Data Squat made me stop watching Digimon. I had a hard time stomaching the shift in artstyle towards something that looks like bad fanart and when I didn't like the story either I just stopped. Haven't gone back since.

I'm looking forward to tri though.

Ranking:

Tamers
Adventure
Frontier
Adventure 02

Savers

No love for Data Squad, so far I'm the only one who picked it.

I like more the original Digimon Adventure, but I think that, in a more critical sense, Tamers is then strongest series.

Adventure > Tamers > Frontier > Adventure 02 > leftover trash.

While I really liked Tamers and Frontier to some extent it was obvious they suffered from poor first halves. But I do like how their stories were more serious than Adventure and 02. The final arcs of Tamers and Frontier were epic.

I really didnt like 02. Was garbage and a fanfair of the first series, nothing more. Story and characters were lame. The egg evolutions broke the normal digivolutions as well as making Onmimon weak for no reason.

Adventure and Adventure 02. I dislike all the other seasons and I don't think it's actually a great anime, but I somewhat enjoy these seasons.

That and how they misused the original kids were probably my biggest reasons for disliking Adventure 02.