I'm loving the sigma 24mm f/1.8 - but I'm a sucker for close focus. For me, it comes down to subject separation - and I love the rangefinder-like bokeh that the wide angle gives me.
I don't like buttery-smooth backgrounds, though, I find them soulless. The sigma allows me to operate with such a short distance to subject that obtaining background separation at f/2 is easy.
If I were you, have a look round on flickr for the various lens owners' clubs. You'll soon see a lens whose images - even the bad ones - jump out at you, and whose characteristics most closely match your shooting style.