What should the next lens purchase for my Canon 7D be?

No one mention 15-85?

Ze.Dong wrote in post #12642495
No one mention 15-85?

Good lens but no constant aperature.

get a fast prime or a 70-200

haven't used the sigma 30, but from what i read that might be a good fit for your crop. the 70-200 f/4 IS has been great and can be had for much less than the 2.8 I or II. extremely sharp, lightweight, small, and unless you need something for indoor shooting, the f4 is great for the money

Keep the 10-22 & 17-50 (or get Canon 17-55) and get the 70-200 f4L IS, superb lens, light weight and excellent image quality, good for all sorts including portraits, I haven't tried it with a TCx1.4 yet.

I have the same set up and I'm really happy with the 17-55 f2.8 and my 70-200 f4L, great combo with my 550D.

Have had both 24-70 and 24-105 ... ended up keeping the 24-105 ...
1) less weight
2) more reach
3) IS
24-70 is overrated and doesn't perform THAT well in low light ... rather get a cheap prime like 50 1.4 than to use the brick.