I have run a number of different ROMs these past few months. I just installed CM 6.1, and I am really impressed. It is super-stable, and some of the features are amazing. To name a few:
-Lockscreen gestures work as advertised. Awesome.
-Pulldown power manager widget. Even includes a button to lock orientation in portrait mode, which is really useful when you are lying on your side.
-Excellent customization options for status bar and LED
No force closes or random reboots. Great battery life from the start with the stock kernel, although I will start experimenting soon. I have found Chevy's 800 MHz kernels to have amazing 24-hour battery life. Suffice it to say that I am thrilled with cm6.1.
My only issue so far is that my apps did not auto-install from the Market, so I had to use Titanium Backup (a bummer for people who haven't caved and bought it).