Good post!
Seeing as we're married, you already know my biggest clash; Arch Enemy, Ensiferum, Helmet and Act of Defiance.
Have been thinking about this one a lot and have come to the conclusion that as I've seen Arch Enemy earlier in the year, Ensiferum before and am unlikely to be able to catch AoD elsewhere, AoD it shall be. Think I prefer them to Helmet also, but it is a close thing. Also, as Alien Weaponry are on the same stage after AoD, it makes sense to be there and ready for them as they are my most anticipated band of the festival.
Vogelfrey and Jesper Binzer is also a big clash but think Jesper will win. There are other fun, medieval, jump around type bands at Wacken.