I started out using ADW, but it got a bit laggy after a few months (I think some extra features slowed it down). Zeam is terrific if you want something lean, mean, and fast. Its only real downside is the lack of themes and a lot of the cool bells and whistles that you find on most other launchers.
My current favorite is Go Launcher EX. It's almost as fast as Zeam, but packs most of the features of ADW or LPP. When you combine that with the seamless integration of GoWeather, GoWidges, GoSMS, GoFacebook, GoCalendar, etc., it's a great package. You can get an almost complete visual revamp of your device, and it's all themed up the same way.
You can backup your settings (Home Screen - Menu - Preferences - Backup/Restore) so that if you flash a different ROM, all you have to do is load the app, then restore the settings from your SD card.
+1 to those who have mentioned using Home Switcher. It's invaluable while you're experimenting with multiple launchers.
Ultimately, you just need to try a bunch of them out, see which one best suits your needs, and go with it. Happy launching!