Having ridden the daytona 675 on both tires, I much prefer the Pirellis. The Q2s for me squirm entirely too much and make the bike feel very nervous. I feel the pirellis have a much more planted feeling. So, cost aside, it'd be the Pirelli everytime for me.
edit: I'm also speaking in terms of track riding. On the street, I can't honestly say I have too much time on the Q2s.