Who are the most powerful pretenders?

[ArkhanTheBlack]

Actually, every titan shape pretender (Size >= 5 + full equipment slots) can be turned into a top fighter by giving them the trample boots. It's great because you don't have to care about any attack stats and can just focus on making him an invincible fortress. You only need to rush to construction 2 for that at the start.
I'm not a big fan of the low HP pretenders. They die too easily if anything unexpected happens. At least that's my experience...