I have two of the iBuffalo SNES controllers and they work great for anything up to Neo Geo/MAME 2D games. Good build quality and a good d-pad. I got USB extension cables last week so I can sit at the other side of the room now. No lag that I can notice, the benefits of a wired connection.
I have a Mayflash 4-way adapter to use my original Gamecube pad, a PS2 to USB adapter to use my original pad for PSX and PS2, a Dolphin bar for original Wii remotes and classic controllers, and a 360 pad for anything else! I guess I've got it covered ?
But yeah, delighted with the iBuffalo SNES pads, recommended.