I'm not super keen on the real big 'freaky' muscular guys, though dated an amateur bodybuilder for a while and it was so funny that he had to walk through doors slightly sideways on he was so wide.
But for a guy with good musculature and defined physique, its knowing how much time and dedication he's put into his training, diet etc that i really admire as someone who struggles with having that real drive for body perfection.
Plus love big arms, chest and shoulders, feels great to be hugged by such a guy, I feel quite protected, but then as a top i love that a muscled guy's ass is so peachy, hard, round and tight and needs work to open up but wow is it worth it when you do. Feels great having your dick in a built guy with a tight hole and also does the ego a huge boost to have a big muscle guy take my dick.