ok i think i'm starting to agree with lildegregs22.
There are different roms with different pros and cons. Ive tried a few now. A question you need to answer....do you want a speed rom, do you want a 2.1 rom (ie the new version of andriod) or do you want a rom with all the bells.
The 2.1 roms are good fun to try but if you value the htc sense UI, (IE the nice stuff on your hero, weather, pc sync, htc widgets) then the rom scene is a little rubbish. IE the roms are slow and or a bit buggy. The vilian 2.1 rom with sense is still young and has some issues but looks like the best 2.1 rom so far. (with sense)
The 2.1 roms will improve once the real 2.1 rom appears.
Some of the vanilla 2.1 roms (IE without the htc sense ui) are great, quick and you get all the advantage of getting the new apps that only work with 2.1 (Like google goggles) but you will lose all the good things that sense brings. (my biggest loss was the pc sync)
There are loads of 1.5 roms and the best i've tries is the modaco rom which is a lot faster than the stock rom with so far with no draw backs (as i think its quite a mature rom) There are of course other 1.5 roms built for speed but the madaco is a good place to start for new rooters.
Hope this helps