I personally enjoy cooking ROMS myself but I have tried
MightyROM in the past and was impressed ... Alot of people here swear by it as well, it may be a good place to start... I believe he has a WM6.1 version, and a WM6.5 version also.
In any event the trick is to just pick one and flash it
.. If you are new to the scene just make sure you read the unlocking and flashing STICKYS in this forum and then dive in...
The best way to decide what features and tweaks are important to you is to start playing around with what's available...
Good luck...