If you flash ROMs like crazy, don't you have an idea of which one you like the best?
Basically, it goes like this:
Backside has lots of customization and fun things in it.
mrg666 / Harmonia for lightweight, stripped down ROMs and the best battery life you'll find on IHO. mrg uses his own kernel though also, and it's looking good.
The others, well, to be honest I'm not that up to date on. tvall has one that has some 2sd scripts built in, but I never usually touch those so I don't have any experience with it, and he also has his own kernel if I recall correctly. This is more advanced stuff though, and it doesn't seem like you need to be touching that yet. Good luck.