......sell 28-135mm and pick up a used Tamron 17-50mm f/2.8 (non-VC).
If you do sell the 28-135 and apply the money to the BB credit, you could also pick up a Tamron 70-300mm VC. Price is $449 new, but they have a $100 rebate going on until 9/30.
I just spent a lot of time researching http:// ….
and came home with the Tamron 70-300 yesterday. I spent this morning taking 120 shots with it and reviewing them. Very happy. The research told me it was better than the 55-250 and non-L Canon 70-300 for build quality and IQ and my eyes verified it today. It is not an L, but it's a great lens, especially for the money. Plus, the extra reach to 300mm is just a kick.
BTW - note in my sig below that me wife has the Tamron 17-50mm non-VC. Got it for her last week (also currently has a rebate) and it is terrific. Helped lead me to the 70-300.
Good luck with the decision - it is part of the fun.
