If you're just looking for a filter - The Evoluzione one is probably the best.
But keep in mind that the Aprilia (Mille, Falco, Futura) airboxes are all too small to make best low/mid power - I picked up 2~6 horsepower from 4K all the way up to 9K (No additional peak power) with the Renegade "Non-Box." GREAT mod - Plus, the additional intake noise is awesome! If you're the 'Stealth' kinda guy, and want to use stock or Road Approved cans, that'll add nicely!
Your choices are:
Renegade Non-Box - Basicaly a flat C/F plate that replaces your airbox. It is not sealed and can draw air from all around. You'll need to pick up a 3/8" crankcase breather filter. K&N and others make them.
Aprilia SP airkit: Probably the Tracnically superior choice - It operates on the same principal as the Rene system, except it preserves the seal. Also comes with shorter Velocity Stacks for better top end breathing. I've not seen any dyno graphs of this one.
Evoluzione spacer kit - Adds additional volume with a small aluminum spacer. Closest to OEM configuration.