My earliest memory of Transformers was the 1986 movie. I’ve watched the original cartoon entirely, and I must say, it sucks. It would have been awesome if I’d seen it as a kid, but now? The movie holds up fine, but not the show. I’ve watched a few of the shows between the original and the stuff now, and my favorite was probably Beast Wars. The story, I thought, was very good, but I wish they expanded more on some of the little things, and ignored some of the bigger things they focused on. Transformers Prime is also pretty good. I haven’t watched any of season 2 yet, but season 1 was good.
From what I’ve seen trying to go back and watch the Unicron Trilogy, it sucks pretty hard. Then again, the DVD releases were dumb and skipped a ton of episodes, and I don’t want to search for torrents for something that bad.
My favorites are the Constructicons (G1) and Dinobot (BW).