No such thing as best, just flash a few and see what you feel brings you the best performance
worst answer ever.
I did unlock/root/flash roms on 30-35 devices, for friends/family and myself.
And even if XDA members do not like ''best rom/kernel'' threads, its very usefull for a quick search, because i.e. my friend want simply a stable rom and I don't want to test every roms or read the thread's 200 pages.
Wihout pointing the ''best rom/kernel'' you might maybe help by pointing the cons and pros .
Here my reply for this thread :
After reading the Franco XDA interview, he was pointing the fact that there's not much work to do on kernel in general, because they are out-of-the box already good.
My first device was a desireZ, with froyo 2.2, back in the days, kernel works was badass, and make huge changes to the devices, but now, I agree that there's not much difference, at least for now, since this OP5 is crazy fast.
I do use Franco kernel, as per Franco's thread, he's stating better battery life. well, hard to tell , since he won't achieve 125% better battery life... It might go around 10%. Which is good, but hard to tell on day to day usage, since 10% is about my usgae precision time if I compare all my usage over each days.
So far so good, no cons.