Location would help but in hi capa land you have a couple options:
5.1
Government - Predominantly black with a few silver highlights
Stainless - 2 tone silver and black (warning, silver finish on the frame peels)
Gold Match - Predominantly black with gold highlights, has serated slide, better front sight, weird floting inner barrel system that everybody removes and angled cut frame. It's a great base if you want to go down the gold bits route.
4.3
Black - Self explanatory
Custom Dual - 2 tone silver and black (warning, silver finish on the frame peels)
Xtreme - It's a customer dual with a black frame and the internals are modified so it only shoots full auto
4.3 vs 5.1?
Only notable performance difference is the 5.1 gets slightly more FPS due to a longer inner barrel, easily solved if you get a 4.3 and move to a threaded barrel, run a tracer adapter and you can stick a 5.1 length barrel through it.
Parts availability is about the same now, there has been a surge recently in 4.3 parts so they're about level as 4.3 used to be harder to source parts for.