Here's my list.
Optimus Prime/Primal: BW,Movie,IDW, Animated and Prime: I like each of these Otpimus for what they offer to the table in some way. I like the more relatible aspects of Primal and Animated Optimus but the wisdom and designs of both Movie and Prime Optimus has impressed me too. It may be cheating but at the same time I like there's something about them I like.
Megatron: BW,Movie,Animated,IDW and Prime: Like Optimus there's a lot I like about what each Megatron offers I'm leaning more towards BW Megs for having a more charming and interesting personatly but I do enjoy the more brutal nature of the movies and Prime as well as the design cues with certain aspects of Animated Megs too.
Arcee: Prime. She's by far my favourite version design and character wise because I like the fact about how she's given a chance to shine on screen for once.
I love how her personalty it tough yet caring so I'm hoping future versions of her will take some cues from her.
Bumblebee: Movie,WFC and Prime: I guess since I've first heard of Bumblebee from the movies I'm actually more connected to him that way as well as Prime Bee but I do like how WFC Bee was handled.
Jazz: Animated: I love how he's both cool and smart and how he developes in the series. He's someone I like to hang out with.
Starscream: Armada, Movie and Prime: I've first heard of Screamer in Armada so I like how he's one of the most interesting character on the show and one of the most interesting versions of him to date,Prime Screamer too has an interesting personatly he has because like Armada Screamer has more things going on with him other then hate Megatron and want to take over. Movie Starscream though holds a special place for me because I'm one of the few people who likes his deisgn and voice.
Soundwave: DOTM and Prime: He has a creepy vibe in both series due to how he looks and sounds and that makes him pretty interesting in my book.
Grimlock: FOC and IDW: These are the versions of him I like best so far because I like how they take what's best of his original bio and G1 show versions and made them into something neat.
Shockwave: Animated,DOTM,FOC and Prime: Like Optimus and Megs I like certain aspects of him. His character in TFA,FOC and Prime interests me and both the DOTM and TFP versions make him look bulky and intimedating.
Bulkhead: Animated and Prime: Both versions has the same lovable but powerful personatly of the character that I grew to like a lot in both shows.
Ratchet: Animated and Prime: Like Bulk both Ratchets have a cranky but caring streak that makes him charming in a lot of ways.
Ironhide: Movies: For being a badft.
More to come.