It depends on the format. The limitation - albeit a small one - of
Stroke of Midnight is that it can't hit lands, whereas
Generous Gift can. I basically play only commander exclusively, so the additional utility of being able to hit a problematic land like a
Cabal Coffers,
Gaea's Cradle,
Maze of Ith, or even a
Reliquary Tower is worth the slightly larger body the opponent gets; in most situations, the difference between a vanilla 1/1 and a vanilla 3/3 is negligible. Honestly, I'd probably run both, and I was excited about seeing
Excise the Imperfect too.
I don't know what the constructed/limited landscape is like for lands (no pun intended), but I expect in those formats Stroke would be marginally better than Gift.