Let's see...... My absolute favorite yaoi pairing would have to be KuramaxKarasu even though I was completely terrified of Karasu when I first saw the series, but then who wouldn't be after what he did to poor Kurama. But I got a friend interested in Yuu Yuu and then she became obsessive over that pair which caused me to develop my own mild obsession too. And if another friend ever read this she would so hate me because she could never stand him having any sort of relationship so close to Kurama.
I am pretty firmly against HieixKurama pairings, though I don't know why, but I have figured out ways to put Yuusuke and Kurama together as well as Kuwabara and Kurama, though I'd need to think back on them. The only one I've really considered for Hiei though would be Kuwabara because they bicker so much more than Yuusuke and Kuwabara do. Then again, my friend and I did try to pair Hiei and Bui once, it didn't quite turn out as well as we had wanted.....
I haven't found any good yuri pairings yet though I really haven't tried to do so to tell the truth. I believe I managed to pair Shizuru and Yukina together once, and Keiko with someone else too but I don't remember who anymore.
I think it's fun to try expeimenting with new concepts and seeing how they turn out, the pairs and all, and the events. It's all jsut so random sometimes and that makes it a bunch of fun.
Oh, speaking of random thoughts; if anyone would like to read something that sounds very preverted but really isn't then go to this story and read it all. It really isn't that long either.
http://www.fanfiction.net/s/2858934/1/ To those of you who do read, enjoy!^-^