10-01-2015, 11:19 AM
All depends on your priorities: The best lens on 50D is Canon efs17-55f2.8IS simply amazing you won't regret expensive yes but worth every penny: Blazing fast and accurate focus, good color rendition, very sharp excellent low light capacity, believe me it will cover almost all your needs. Only drawback it's not lightweight.
If you are into compromises the 18-135 STM is a good bargain as stated.
Also note Canon 17-55 is a very reliable lens, it's the only lens I owned that didn't need repairs in six years despite daily use. This is one of the lenses you can buy used. I wouldn't recommend buying a lens like Canon 18-200 used or without warranty for instance since provability it needs repairs is quite high
If you are into compromises the 18-135 STM is a good bargain as stated.
Also note Canon 17-55 is a very reliable lens, it's the only lens I owned that didn't need repairs in six years despite daily use. This is one of the lenses you can buy used. I wouldn't recommend buying a lens like Canon 18-200 used or without warranty for instance since provability it needs repairs is quite high