If we look at the tv show, then its definitly Angel.
Riley's moved on and happily married (Buffy seemed okay with that), Spike is still believed dead by her (and she's moved on from his death) and Xander was never in the running really.
But the comics did a pretty good job of assassinating the whole Bangel thing, (how anyone can read the 'Twilight arc' and think that DH is Bangel is beyond me...) and Spuffy dies a slow, boring death during S9, so none of the above. 🙁
Buffy probably still has strong feelings for Angel but their mixed up with all sorts of other things. Buffy and Spike are friends-ish with mixed/confused feelings of intimacy (but not love), and Buffy hasn't had any real significant romantic encounter in the comics other than Satsu.
In the comics Buffy's love life seems open for something new and different.
Personally I think that Buffy has already met the love of her life, her perfect romantic foil, she just hasn't realised it yet. 🙂