I have only had my Vega a few days but have tried most of the roms out there.
Modaco R8. Quite nice. Seems fast and stable and would be my main rom if Corvus5 didn't exist.
Vegacomb. Looks beautiful and I will use it as my daily rom as soon as a few oddities are ironed out - amazing work!
CM7. The couple of nightlies I tried seemed buggy and had essential items missing.
Corvus5. The most enjoyable, complete and stable rom and I've always come back to it.
Smartphone History. Nokia 9110, Nokia 7650, XDA, XDA2, XDA2i, XDA2s, N95, E71, N82, iPhone, iPhone 3G, HTC Hero, iPhone 3GS, T-Mobile Pulse, iPhone 4, ZTE Blade, Motorola Defy, Google Nexus S, Dell Streak 5, Samsung Galaxy S II, Samsung Galaxy S III