At first I was an IchiRuki fan, but I completely converted to RenRuki after seeing their past and current relationship. Even though a lot of people think of them as siblings, I think it's absolutely adorable. <3 I also support IchiIshi, ChadHime, TatsuHime, and to a lesser extent, IchiHime. I'm also warming up to ByaRen, though I'm not completely sold on that yet. But I'm not too far into the series, so there's still time for me to like it. I see a few other possibilities as well, but like I said, I'm not far enough into it to officially like them.
Grimmnel is one of my favs. It's actually not that crackish and there are quite a few fics on it. I can just see these two bickering all the times. Grimm tries to act all tough and nasty, but then get's whacked over the head by Nel for his stupidity at times.
And then I support Ichihime and Renruki. I like renrukia a lot, as Renji would have a harder time revealing his feelings to Rukia, seeing as he doesn't want to get killed by his older bro and whatnot.
I also support Hanataro/Hinamori, Komamura/Soi fon (friendship), Kenpachi/Unohana, Shunsui Nanao, and Ikkaku/Isane (don't kill me!).