which camera are you using? Canon makes really good glass, probably the best, but you can only use them with canon cameras, so you should know which camera you are using to make sure you get the right lenses. And Canon can be a little spendy. Tamron, Sigma, and Phoenix make decent lenses for most cameras out there and they are a little more reasonable priced. Really depends on a few factors like speed of the focusing and such for the higher priced lenses.
HTH