For me scrubby zooming is preferred (coming from Photoshop), but it is way to slow. I have to move the pen on my tablet back and forth a few times, whereas in Photoshop it's much more sensitive and therefore a lot quicker (I don't need to lift the pen/mouse and get a very wide zoom range). Gets annoying after a while. I can see why some prefer the marquee zoom in this case as its currently quicker than scrubbing.
Photoshop uses both command+space and option+space (latter does not interfere with Spotlight) and has a dedicated setting for scrubby/marquee zooming.
