A lot of us are using GSB 2.x right now. It's a Gingerbread ROM that's fast, smooth, and very stable, at least for most people. There is also xtrROM and xtrSense which are 2.1 based ROMs that are also very fast and stable. They're based on the stock htc sense from the Eris. The downside with these is that they can sometimes slow down like a stock Eris after some time. For froyo ROMs, CELB and Froshedyo are very stable and fast ROMs. Froshedyo is on its final release, but CELB was just updated.
I would recommend giving GSB a shot. Just make sure to follow the installation steps in the thread on xda. You have to flash a google apps package right after flashing the ROM before restarting the phone.
If you have any other questions, feel free to ask. I'm sure more people will chime in soon, if they haven't while I've been typing.