Favorite musclecar for me; there's no such thing, I like them all.
However, I do have a soft spot for Phase III GT Corvettes, '69-70 GT500 Shelbys and 1970 Z28's.
Cars I owned, or my parents owned, that I wish I had: I wish I could find the 1969 Grabber Blue w/white interior GT500 that my parents bought new towards the end of 1969.
Car that I personally owned that I wish I had back would be either my Forrest Green '70 Z28 or my 1968 Camaro SS/RS 396 that I had a Lingenfelter 461 installed in.
I guess my all time favorite musclecar would be the 427 Cobra though, if you consider them musclecars.