I'm thinking the Tamron 17-50/2.8. It's literally the best all round lens which doesn't go deep into your wallet. See Bryan's review. I started my photography with the Canon 17-85, it is reasonaly wide but the distortion is very noticeable at the wide end, so not very ideal. The 28-135 is a nice lens, but just may not be wide at all on a XSi.


Still around yourbudget, you can bag yourself a Canon 17-40/4L - this could be a lens that you will keep forever. 40mm may not be long enough but it has to do with your taste.