I prefer to bottom! I guess I had a really good doc give me a circumcision at birth. Really managed to cut most (if not all) of the pleasure nerves so that topping a guy isn't all that magical. Its actually pretty desensitized, which is great for the receiver as I can go a loooong time without cumming. Yet all the nerves are still there in the ass. And it feels absolutely amazing to get fucked. So from the pleasure stand point, I most definitely enjoy to bottom.
But what really sux is that oral, hand jobs, etc are also desensitized. I love to make a guy cum but its VERY difficult for a guy to make me cum. But being a bottom doesn't exactly make you passive... I really like to be a "take charge" bottom. Nothing like tying your partner up to the bed post, work his body, then ride him to near climax, and then jump off and work the nipples or taint. Then jump on the ride again, and again, and again, all the while he is at your mercy to cum.