Depends on the ride quality you want - I run 18's with 215/35/18 tires as well as Eibach Pro springs and Tokico Blue shocks and its a bit bumpy a ride.
So I would think 17's are best if its your daily and your streets are not the greatest but if you usually drive on smooth roads I'd get 18's. I like less rubber cause IMO it looks better.
Hey, I'm happy with the stock 16's, but if you're going to go aftermarket, 17's appear to be a good compromise between up-sizing for style and drivability.
