I currently have a Canon T3i with a 50mm f1/8, 18-55 kit, and 55-250 f/4.0-5.6. I love the 50, but outside of setup shots, I seem to grab the 18-55 mostly just for the flexibility. (Mostly used on the wide end.) For my next lens, I'm torn between a Tokina 11-16 2.8 (fast, sharp, and wide) and the Canon 15-85mm f/3.5-5.6 IS (USM and flexible).
I only have enough budgeted before my next trip (San Francisco) for one lens, and I'm torn. I probably won't bring every lens with me when travelling, which has me leading toward the 15-85; my question is more: so is there anything I'm missing or should consider? This will be my first "quality" glass. I don't plan on going full frame any time soon. I could just rent both lens for a few day and see which I like more; but that would delay the next purchase....
Of note: I don't plan on bringing a tripod or monopod with me while travelling, which means either wider aperture (2.8 on Tokina) or IS (15-85) would make a big difference when shooting night/indoors... I don't know which would work out better for me.
edit I went with the Tokina, gives me a the missing piece of range; and will give me an alternative to my 1.8 in lower light situations (Where I've been mostly using kit 18-55 due to 50 being too tight)