I started collecting because of this line, well, mainly classics and universe 2.0, but it all falls under the same umbrella. I blame Rodimus!
My three favourites for display, in order, would be:

United Jazz - Chalk another one up for this guy! The best representation of G1 Jazz to date. He looks extra sharp thanks to the metallic details. Solid silhouette.
United Stepper - Basically flawless. Striking deco and details, love the colours. Displays perfect.
Henkei Smokescreen - Classic transformer form with an interesting and understated colourscheme. Just lovely.

To strictly talk about Generations only figures, I'd go with Thundercracker, Thunderwing and Thunder Sky Shadow.

Honestly though, this line has so many awesome figures. I'm in agreement with a lot of people's choices so far. Lugnut, Mirage, Cyclonus, Tracks are all fantastic too. Gosh, us ozformers have got some good taste!

Quote Originally Posted by Gasaraki View Post
I'm surprised you list United Megatron over Henkei ver... I don't own the United one, but in pics Henkei seems to look better. Is it different in person??
Slightly different. Alfes2010 has some good comparison shots on his blog. I think United looks a little nicer as it's missing the weird red/orange paint apps. Although, he could do with getting his "angry eyebrows" back. Sorry for cutting in Bidoof.

Quote Originally Posted by Gouki View Post
The biggest drawback for Jazz is that his chest doesn't lock in. If it weren't for that it'd be hard to beat.
Yes! This is super annoying on the RTS version, as with the Gift set redeco. They fixed this on the United Jazz though. I don't know how, but it works.