I don't think the Tower is stronger than the others in the trio; it's just that they have a better chance of winning on larger maps (I know it's debatable, but that's what we're here for).
1. There's always meat available. Definitely!
2. Necropolis is more likely to be in the Dungeon if it's available... at least on random maps... maybe it's just me?
3. You can level up diplomacy through battles, and you don't have to spend money on upgrades... in the end, they join regardless of the upgrade level...
4. You might not have time, or you might, if you don't have problems with clearing and resource gathering (and there shouldn't be any problems with that for the Tower from the beginning of the game!!