Tidus and Yuna
purely because she falls in love even though.... well u know.... and that last scene, yeah it brought a tear to my eye as well!! and also the fact that the love runs thru 2 games! (i know its the only true sequel!!)
and as for Rikku and Gippal? well it would look like they had a thing in the past, but it would prby be more like Gippal was an old forgotten friend of cid(10/10-2) and brother and was concidered an uncle....OR.... they were just childhood chums who loved taking the mickey outta eachother!