Statosphere is very underrated. Get Him

 

this..........cause that's what i did.

 

Long Haul or maybe deluxe sideswipe.

 

I'd say the big winners from the ROTF line are:

Leader Prime (though that is above your stated price point)
Voyager Starscream (I feel like I don't see this figure mentioned often, but he is really fantastic... a big improvement over the 2007 version)
Deluxe Sideswipe
HA Bumblebee
Scout Ransack
Scout Knock-Out
Scout Nightbeat (seriously, I LOVE this figure... and his original Detour/Deadend version isn't bad either)
Deluxe Breakaway/Thrust
Deluxe Dead End
Voyager Long Haul
Deluxe Skids/Mudflap... both Ice Cream and regular flavors

 

Even though it's above your price point, I'd get Leader Prime...perhaps someone on the B/S/T Forums could help you out. In your price range, I'd get Voyager Long Haul. A buddy of mine has it, and I'm more than a little jealous. As soon as I find one myself I plan to add it to my collection.

 

I have to agree - Leader Class Prime or Deluxe Sideswipe are my faves thus far.

 

Starscream, as WhiteMocha said, and in my opinion, the Twins! Skids and Mudflap are neat little guys, be it the Ice cream truck or the Chevy Versions

 

HA Bumblebee is awesome if you like alternators-style Transformers. Very solid design, very high quality.

If you can't swing that price point I also really like the Voyager Megatron, who was mentioned earlier. His 'bot mode is quite menacing and the best version of movie Megatron.

 

If you can swing 35$, get ROTF leader prime from walmart.

If not, I really like the legends Prime  

 

get one of the scouts, they don't disappoint

 

Wheelie or Chromia, no doubt, they're so popular the stores made sure to stock up extras of those figures, so I'd say go go go!

 

My top choices would be Deluxe Sideswipe, Voyager Demolishor and Human Alliance Bumblebee.