If you're just playing the games on a PC, sitting at a desk, and have a mouse available to switch around games, then MAME32 is the easiest. If you want something to put in an actual arcade macine, GameLauncher was the easiest for me. It's clean and professional, too.
MAME32 in a cabinet would look VERY unprofessional IMO. Who wants to see Windows running on the cabinet? If MAME32 has a cabinet mode, I've never seen it.