Well... me personally... I just fell in love with the lines of the QP the first time I saw it... that ass... just gorgeous.
My dad had the pre-facelift Z4 3.0i, but a manual, still with the CDV, and a roadster of course (pre-facelift, weren't you paying attention?). Nice car, very pretty with the top down, a joy to drive once you got past 1st gear and all that... but with the top up... nah... not the drop-dead-gorgeous experience I got from the QP.
And that's where the E89 comes in... If you just take the looks into account, it looks like a roadster when the top's down, it looks decent with the top up, a lot better than the E85 with either soft- or hard-top, but still it just only looks decent with the top up... nowhere near as pretty as my beloved E86... a future classic...
This is why I bought the E86. If I want the open-air experience I'll take my bike (that's a pedal-bike, bicycle, whatever...). The arenaline rush I got from driving a motor-bike, I also get from driving this car.
Can't you all see? I'm still in love, no point argueing... so, x2, QP, topic closed, seriously