That depends on your preference for combined height and g1 appearance or not. UT combined height is around 17.1” with a g1 toon look for the bots. Zeta combined mode is constructor height with a mixed bag of influences, big chunky bots, and different alt modes. I like Ut for the bot modes, but don’t like how he looks next to constructor. I like Zeta for combined mode since it looks great with constructor, but don’t like the bot modes. So if you have 15”-18” combiners and like g1 toon, then Ut would fit well. If you want a monster combined mode with weak bot modes then zeta would fit well. It’s a hard choice since neither set does it “all”.