My favorite color of M.U.S.C.L.E. figures has always been neon green. No matter what other color it's next to, it always makes for the most eye-catching figure on the shelf; green M.U.S.C.L.E.s almost look like they could be glow-in-the-dark even though they aren't. I recently added green versions of some of my favorite sculpts in the line to my collection and had to get a shot of them all together. Interesting thing to note: The Planet Man figure (third from the right) seems to be a factory error, with his head tilted to the side in a way that makes him appear a bit wonky and drunk!
For more M.U.S.C.L.E.s, check out the original post I did on the line.