nstallion is correct. The answer to your question is very subjective. Ask 10 people and you're bound to get 8 different answers. And kernels are the trickiest part. What works with one particular ROM on one person's phone won't necessarily work on your phone. For me, P3Droid kernels work best (they're the only ones I can use above 1.0Ghz). I'm currently using JRummy's Kangerade - NexTheme (found in ROM Manager). On my phone it has been the most stable. I'd also suggest you try out the Froyo ROMs from ChevyNo1 and Bugless Beast (both available in ROM Manager). The only way you're going to find out which is the most stable Froyo ROM is to try some on your phone.