How can I decide which lens to prioritize between Tokina 11-16 or Canon 15-85?

Question

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)

Answer 1

Look through your recent photos. Which scenes could have been captured better if they had been shot with one of the candidates? Also, think of photos that you could have taken, but didn't even try due to limitations of your gear. Ditto with ideas that you could turn into photos in future. Which lens would help you with those?

Pick the lens that will bring you more good photos.

Answer 2

Those two lenses are not in the same category.

The 11-16 is an ultra wide - this will let you take pictures you can't today - you should get this if you want to take really wide angle pictures (that is not slightly wider than your 18-55 at its widest) and unless this will become your favorite photography style this lens will not be your primary lens.

The 15-85 covers a very useful range from a wide to tele, it will not let you take pictures in a style you can't today (it does give you the 15-18 range you don't have today but it's nothing near as extreme as 11mm) you can think of it as an higher quality replacement for your 18-55, it's a useful everyday lens and you can even take it as your only lens while traveling without missing too much opportunities (with maybe another backup lens and maybe the 55-250 for when you need the longer zoom - if you like to shoot tele).

So:

• If you like wide angle go for the 11-16 (maybe after renting it to make sure you really do like wide angle).

• If you don't like the image quality of your 18-55, you want a flexible lens you can keep on your camera all the time or if you want it just a little bit wider then 18mm go for the 15-85.

Full disclosure: I don't have and never used any of those lenses myself, I don't have any lens wider than 18mm so I don't really know how wide is 15mm - and, just so you know what my bias is, I really want to get an ultra wide lens for myself.