Kaldir looks better since it's a blizzard tileset, but my problem with using Kaldir is that:
1) My planet is not that frozen. It's just a winter setting, not the most inhospitable planet in the koprulu sector.
2) I'd have to buy another copy of HoTS to host everything online. Plus the campaign wouldn't be compatible with WoL.
I think that depends on what you want to present with the final tileset. Your tileset looks earthlike, like a cold winter in northern europe/russia. the HotS tileset looks even colder, like the north pole, but the cliffs make it look more like an alien planet.
Hmm, for Difficulty of Mission Two. Either add more Anti-Air for the Zerg, or take away the player's ability to use Air. I just brought in like 5 Void Rays and completely steam-rolled the entire map. Noticed there was a ton of Ultralisks standing guard though.
Gonna test the Third Map now.