Lewyn

+Spd. Lewyn wants to utilize Forseti's guaranteed doubling effect as consistently as he can.
Since he shouldn't be taking any hits, his defensive banes don't really impact him as much.

Question of preference. I think I actually like +atk better because he's probably outmerged against the fastest threats he can encounter (ex: Nino) and won't be able to double even with a boon, so may as well try to hit harder against the units that he can double (some of which might actually have good res, like Sheena)