I have a Dunlop Hendrix wah and a Mini Crybaby. The Hendrix is a great wah, but I adore the mini. Small footprint, with a 3-way internal switch to alter the voicing, it's fabulous.
+1 to Ace & blueman for a used 535Q. It may not be the best sounding wah on the market, but it's really flexible and can be found pretty cheap on the used market. I've heard good things about the MC404, but it's more recent and used prices are still relatively high. I'm thinking of tracking one down for the switchable inductors and because it doesn't sound all that similar to my Wilson Signature.