If I am doing a long smoke in my stick burner I prefer to use oak. The flavor is great, and the woods are full of oak trees in my neck of the woods. For an intermediate cook I will use charcoal with hickory or mesquite chunks from the store. Lately though, I have been mostly cheating and using my electric smoker. It is so much easier and I can actually sleep through the night when trying to do a pork butt or two.
I have done quite a bit of pork and beef, but have not experimented with any fish yet. I think the first thing I am going to try is Asian Carp. I have heard mixed reports on their edibility.... only smoke and time will tell. Has anyone ate one of these before?