Futuristic vehicles. Super-realistic stuff just makes me think "Well, if I wanted to see that, I'd buy a model kit." Cybertronians seem more 'natural' to me when they have non-Earth modes.

I don't mind robotic animals, but the original BW stuff never really appealed to me for much the same reason that many of the smoothly-curved altmodes don't - they tend to end up with too much hull kibble for my taste.

It's a balance, for me. I like altmodes which result in minimal motion-blocking and sight-blocking kibble for the robot, but which aren't so heavily weighted towards the humanoid mode that the altmode is obviously just a robot lying down or something. I'm even OK with fairly large kibble like G1 Scourge's wings and BW Rampage's claws (the shoulderpads and crab legs are another issue).

Oddly enough, I don't mind the altmodes of the G1 Constructicons, but only as altmodes of Devastator - it's kind of neat to see such a large technokibbled robot turn into a set of very non-kibbled machines.