Everyone's opinions vary on what makes a good ROM.
Best thing to do is always go after a developer that is well known ( I understand this is impossible at first, but over time you get familiar with who's who of development)
Look for good reviews and comments from users and last but not least some trial and error. I normally direct new rooting and custom ROM users to download a few and place them on your sdcard, and take them each for a few day test drive
You can then see a little variety of what is available and make a decision at the end of a few days as to which you like the best of a few ROMs.
Don't forget to make your Nandroid Backup's so you always have one to restore back to in case something goes wrong or you just don't like what you end up with
Happy flashing