Need advice about what lens to buy

Hello.

I need your help in choosing a lens. I do a lot of concert photography so I'm looking for a fast lens. I also do a lot of portraits.

These are the options I'm thinking about:

Tamron AF 28-75mm f/2.8 XR Di
Sigma 24-70mm f/2.8 EX DG Macro DF

Tamron 70-200mm f/2.8 Di LD (IF) Macro AF
Sigma 70-200mm f/2.8 II EX DG APO Macro HSM AF
Pentax DA* 50-135mm f/2.8 ED (IF)

I think the normal to telephoto are going to be more useful. But I'm not sure. Do you have any kind of feedback on these lenses? Any other recomendation??? should I go for a prime instead?

I've always digged the Pentax 77 f/1.8 ltd. I think that focal lenght is nice for portraits and concerts also.

Any kind of feedback is welcome.

I own the following lenses:
Pentax 50mm 1.4
Pentax DA 10-17mm f/3.5-4.5 ED (IF)
Pentax DA 18-55mm f/3.5-5.6
Tamron AF 75-300mm f/4.0-5.6 LD