I heard before that the latest AOKP was the most stable ICS ROM, now what is more stable AOKP, or the new ICS CM9?
Depends on the person. Though I talk with aeroevan everyday casually and about ROM development.
I have run almost every one of his ROMs. I have seen what he does to his ROMs. I haven't talked with anyone from AOKP or ever seen a change or worked with anyone from AOKP my self. So of course I would pick CM9 over AOKP Any day.
On the actual ROM side. They are very close. But I find that CM9 has just more working. And aeroevan fixes easily 2 things a day (Even if he doesn't public release a build) And I have yet to see my Inc2 Crash on CM9.
And I run power hungry games and have my phone overclocked. So in the end it really depends on what your looking for in a ROM. I like CM9. I like aeroevan, and I trust him.
So that's my reason for CM9. But I wouldn't say one is better over the other since at this point it is really based on preference. Although I have installed the AOKP ROMS. I normally switched back withing 2 days max.
So just download the latest from both and experiment I guess and figure out which you like for your self.