Can vouch absolutely for the 28mm f2.8 as a brilliant walkaround lens on APS-C. It equates to mid 40's focal length, which is closer to a true 'standard' lens than 50mm or worse, 50mm on APS-C.
Sharp, compact, cheap, and fast focusing despite perhistoric AFD motor.
I loved mine and may well buy an another.
It's now officially discontinued, so you may have to pick up used. There is a new 28mm f2.8 IS USM coming, but Canon seem to have forgotton that theres a recession on and priced it at silly money: its a very specialist lens these days, most folks using zooms, but priced right they could sell a fair few, I will not be buying one.