I tend to favor friendship pairings over romance/sexual pairings when it comes to Reno. I just have this nagging suspicion that once a relationship gets sexual, he doesn't take it seriously, but he'd be loyal to a close friend to a fault.
In that context, I like Reno/Yuffie, because they're both such smartasses and I think they'd play well off one another. I'm also fond of Reno/Elena to the point that it kind of dominates my more recent fan fiction.
If we have to go the romance route, I don't absolutely loathe Reno/Rude or Reno/Elena, and even Reno/Tseng to a point... but like I said, I favor friendship pairings.
I don't like Reno/Tifa, because frankly, I just can't quite wrap my head around that one. I could see her maybe eventually forgiving him for obliterating Sector 7... but not to the point that they'd be close. I also dislike Reno/Yuffie as a romantic pairing, because... she's like 16 in the game. That's a little creepy.