Gotta love the T-51 original. I'm still irritated that Bethesda didn't understand that the brown circular bit around power armor users' necks was a cowl that's part of the helmet. It adds to the whole whole sealed gas mask/protective suit aspect of the PA.
I do kind of like the design of the T-60 as a better version of T-45, but hate that they jammed it into the lore so terribly and thoughtlessly. I think the T-60 with the Atom Cats paint is the best looking suit in Fallout 4, but that's kind of like winning an ugly dog competition.