it would help to know what you got..... sideswipe or skidz/mudflap (get one you have to get the other) skidz is a very fun figure, just a bit complicated to transform at first, got to get mudflap soon
I don't know who you have, but I picked 'other' for Rampage or Sideways. I have them both and I love them. I did a little paint app adding with a silver sharpie to both of them, which brought out a ton of detailing. Great figures, but maybe you already have them. Shrugs.
I voted Ravage. If you could only pick one of those from the list, he's the guy to get in my opinion.
Ravage is badass, I'd get him among those listed. Among the others listed, Chromia, Skids and Mudflap are my other favorites. As echoed by others, if you haven't picked up Sideswipe yet you definetly should.
Alright now that a poll is up, I say go with one of the twins or Chromia. (Voted for Chromia in the poll)