I had to go with Garfield/Stone. I loved Ed Norton/Liv Tyler but its just so unrequited. Banner goes into hiding and their love is put on ice. Not that Peter and Gwen's fate will be much better.
To make myself feel better I'll rank the ones listed:
1. Andrew Garfield/Emma Stone (Marc Webb knows his young love. And probably loss. :/ Not to mention great chemistry here)
2. Ed Norton/Liv Tyler (unapologetically passionate and emotionally-strung. But unrequited in an unfortunate way)
3. RDJ/Gwyneth Paltrow (Felt real, despite all the craziness in their lives their relationship felt grounded)
4. Chris Evans/Hayley Atwell (Short, sweet. Also unrequited. Never to be requited.

Shame that)
5. Henry Cavill/Amy Adams (Surprisingly appealing. Best incarnation of Superman love I've seen)
6. Bale/Hathaway (Decent. Nothing too too special)
7. Keaton/Pfiefer (Classic, fun)
8. Hemsworth/Portman (rushed, unrealistic, but cute)
9. Bale/Homes/Gyllenhaal (meh.)
10. Maguire/Dunst (Awful in many ways. Awkward and too much of the trilogy's focus.)
Honorable mentions:
*Hellboy & Liz Sherman* (particularly in Hellboy II)
*Xavier & McTaggart* (am I the only one who saw it?)
*Hawkeye & Black Widow* (!!! cannot wait to see more)
Rottenest eggs:
#BDH's Gwen Stacy/Eric Foreman's Eddie Brock# and all that love quadrangle nonsense.
#Reed Richards and Jessica Alba# BLEH hit me in the eyes with an iron poker. NEXT!
#Shadowcat/Iceman/Rogue# What a waste of Ellen Page. Stick her with Colossus for cripes sake.