I'd have to go for Skeletons..
Although aren't skeletons basically zombies anyways? lol
Either way.. Neither are very... uh "Xenimus-like" which isn't a bad thing, in-fact better gfx would be good
and plus, the zombies are only using their fists to fight (Thats what I'm guessing lol) so I wouldn't think they would be very strong (Realistically lmfao) for high levels and wouldn't be very fun for long (kinda like the usual skeleton leveling you do in xenimus from 2-5 or so)
BUT if you do plan on adding some special stuff on the zombies(like adding magic powers.. Maybe add teleport/bubble and the usual magic attacks.. And it would Probably give you a reason to add more and more spell attacks) I guess I would vote for them mainly just to see somthing different in Evidyon, since we already have skeletons lol..
But for now I'll stick with the skeletons since they look like they would be rly rly tough