I read mostly J2, though I like wincest too, but wincest has a lot more room for angst and I don't always feel like angsting. J2 can be stretched any way :)
I don't read gen cause I prefer the show's canon (meaning I don't even read the books about what happened before, or the comics, and whatever there is, even if Kripke OKs them)
Toppy Jensen all the way, like, BDSM toppy, I guess cause Jared is taller :) But toppy Sammy, cause... you know. Dean.
SamnDean and JensennJared when I talk but JarednJensen when I write, and not cause of the tops but that's just how it flows.