Lens Recommend ?

[Canosonic]

Hi there
I was wondering in getting a new lens.
I already got these two:
Canon 18-55(with the 400d)
Sigma 70-300

I am stuck at thinking which one to get: sometimes 18mm wide isn't enough
and sometimes the quality isn't good (no IS) and sometimes i need that range
between 55 and 70.Oh and sometimes (aperture) the lens are too slow.
I have done some research and here is what i got
Canon 50mm 1.8 (very fast and cheap) - 90 pounds
Sigma 10-20 (Wide zoom) - 319 pounds
Canon 28-135 IS USM (that little between) - 416 pounds
and at last the one i dream of
Canon 24-105 L IS USM (yeah the one with the red ring but cost an arm and a leg) - 870 pounds
Can anyone help decide?

 

[JustAnEngineer]

If the 18-55mm kit lens is too slow or not sharp enough for you, how about the Tamron 17-50mm f/2.8?

If you want something wider, how about the Tokina 11-16mm f/2.8?