O Gundam. Get it. NOW. Seriously, everyone who collects Gunpla should have that kit. It's soo much fun and cheap!
To give a really good recommendation, we gotta know what shows you've watch/prefer. I'm just gonna throw a few out there and maybe one will catch your eye:
I recommended MG Strike/Strike Rouge on another one of your (ubiquitous) threads. The Zeta 2.0 has pretty much the same display base/catapult deck, but its quite a bit harder to assemble than Strike. Its looks are unique in the Gundam-verse and is personally my favorite! Any G-Gundam MG (God/Burning, Shining, Speigel/Shadow, Master) have complete inner frames, actually some of the best Bandai's ever done, and they're dirt cheap. Now, the hatch doesn't open on 'em because they have removable Core...Landers(?) that are pretty nifty display pieces in themselves. Also, they are amazingly articulated and hold their poses very well. If you're into Wing Gundam, try the newest Wing Gundam release, as the ver. Ka. has some serious flaws. The 2.0s (Mk II, GM, Gundam, Zaku, Gouf) are all really well detailed, easier to build, have complete inner frames and are flexible. Unfortunately, you have to pay for all that, and they can get pricey. If I were to pick one of the 2.0s to get (other than Zeta) I'd buy the Mk II - I have and its awesome!