I've played the game (this one and SVZ2) quite a bit on 3 different devices and currently have level 11 peasants and dwarven bombers in D&D. My goal is to have allies that can mow through waves as quickly as possible while including both melee and ranged so flying opponents aren't a pain. I ran some numbers and it actually seems like assassins would be the best ranged unit (looking at damage-per-second per leadership spent), and peasants remain the choice as cheap tanks. Is that a decent setup? Here is what I'm looking at:
Peasants + Assassins
Peasants + Dwarven Bombers + Spearman
Peasants + Dwarven Bombers + Spear Horseman
Peasants + Elven Archers + Bowcaster
Assassins + Spear Horseman
I typically use the warrior if that matters. I've upgraded spearman and spear horseman in SVZ2 and they have advantages/disadvantages. I'm not sure I'm sold on one over the other at present but am open to suggestions.
Note Assassins aren't currently a real option as I can't seem to find them (sounds like gift boxes are bugged per other posts).