What's a mecha proportion or design element that you have a lot feelings about? For example, I find it matters a lot to me for more traditional humanoid/Gundam-style designs to have shoulders raised above the collar line and a protruding chest, as exemplified by the Gundam Mk-II
This is such a surprisingly difficult question mostly just due to the fact that I like SO many weird mecha body shapes. I've been rolling the question around in my mind and I'm thinking about like, what I like and what I don't like, and it's so hard to pick elements that I have a lot of feelings on in particular because so often there are examples where I think a thing can be done good and bad, sometimes even on the same design (See: Me liking the Evangelion designs most in Anima, then in TV next, but not really that much in Rebuild, in spite of the fact they are all Ikuto Yamashita designs).
Even my go-to feature for why I didn't like certain designs was that I don't like mouths. But that's not always true! I like Big-O! That has a statuesque face sure but it is still a face with a mouth, same with RahXephon. And then, sometimes I've felt weird about eye design, where I don't necessarily like robots having an iris/pupil, even on designs I otherwise like, like Giant Robo's OVA design. HOWEVER then I don't have a problem with the G Self's eyes, if anything I LOVE the version of the eyes in the films wherein they emphasize the eyes having an iris. For a lot of examples of things I would technically 'feel strongly' about in either direction, there are also examples where I can feel the opposite, so it's really hard to pick things out! Hell, I'm looking at my robots in my room, and there are SO many that like... vary greatly.
I guess ultimately and I'm sorry for the cop-out of an answer but it's REALLY very dependent on the design for me at this point!
Like, I love all the robots I get, obviously I wouldn't be spending my low amounts of money on so many robots if I didn't care about them. But like! Looking at the bodies and proportions of various friends that are on my TV stand:
We've got the Jehuty, a very smooth organic videogame friend, and the Mika Akitaka Blassty, a more classical 80s videogame mecha design, I've got the Ideon, an Okawara design that's very vertical with its tall shoulders, next to the Daisy Ogre, an Ippei design that is squat, wide, and lacks a distinct head. The Dougram with its Canopy head, the Dragonar 3 with its EWAC disc-shaped head, the Scopedog with its tanklike construction, and Nagano's organic Brain Powerd designs, as well as his earlier Ashura Temple from L Gaim. There's also a Zoid (The Gun Sniper) hanging out in here, and the Madox 01, which is a powered armor.
My tastes just vary so much that finding specifics that are always a constant is just hard for me now! And I wasn't like this always, I used to be more discerning, idk what happened but over time I just started getting more and more into mechanical design and then evaluating specific artists just kinda started widening my palate. This isn't to say I'm always a fan of designs, even if I don't dislike them as much as I used to, I admit that Hasegawa's designs for Crossbone Gundam and its various spinoffs never really grew on me, and there's a few other artists that end up more mixed, but honestly! I just. Like mechanical design.
Sometimes I feel bad about it, because like, normally I associate experiencing things with getting a more discerning taste, but ironically enough for Mecha it's been the opposite, I used to have very specific taste and it's just expanded wildly over time as I studied mechanical design, watched more anime, looked at the art of various artists both in settei form and in their full unrestrained illustrations, etc. VERY FREQUENTLY I love designs from shows I despise because I've become so just... specifically design and art focused rather than necessarily even caring about their context, though the context can always make me enjoy a design more.