15-85 f3.5-5.6 or 17-55 f2.8?

Hello,

I have been shooting for about one year with my T3i and I am looking for an upgrade to the 18-55 kit lens.  The kit lens is not bad, but I would like a little more range and a little better low light performance.  Seems I can get one or the other, but not both.  For outdoor use the 15-85 would be very appealing, but moving inside I would want the 17-55....

I do have a 50 f1.4 and a 15-255 IS as well.

I know this is a personal/how you shoot kind of question, but I am hoping for some input on what would be more useful.

Thanks.

M