Another alternative might be the new
Tamron 60mm f2 macro. It has almost the speed of the
Canon 50/1.8, plus the 1:1 macro capability of the Canon
EF-S 60/2.8.
I haven't tested one yet (though I hope to pretty soon), but I have played with one and it seems like a well built lens. Pretty small and light and the fastest macro out there. 60mm is a good focal ength fpr portraits on an APS-C crop camera.
BTW I think I'd now revise my earlier statement and recommend the
EF-S 55-250IS over the 75-300. It has stabilization (a big plus) and it's pretty sharp.
If you don't need macro, the 50/1.8 is still a real bargain at under $100. If you do need macro then either the Tamron or Canon 60mm macro lenses would make good choices.