I've got a MP-1 (Hasbro) that will fall down of its own accord, can't hold it's weapon(s) properly, and is just finicky as hell.
I just sold my MP-4 because I have no use for it and need the space, and am happy with my multiple iterations of the MP-10 mold (Hasbro MP, Takara MP-10B, Hasbro YOTH).
Now if we could get a MP-10 version of MP-4S (without the trailer), as a fan of the 86 film, I'd be happy as a pig in shit. Throw in the purple Megatron gun, and I'm sold.