As I understand it as a Pentax user I have a available to me this range of Standard Zooms:

Pentax DA*16-50
Pentax DA 17-70
SIGMA 17-70mm F2.8-4 DC Macro OS HSM
SIGMA 70-200mm F2.8 EX DG APOMacro HSM II
SIGMA 17-70mm F2.8-4.5 DC Macro
SIGMA 24-70mm F2.8 IF EX DG HSM
SIGMA 24-70mm F2.8 EX DG Macro
Tamron 28-75mm SP AF F2.8 XR Di LD Aspherical (IF) Lens
Tamron 28-75mm AF F/2.8 XR Di LD[/SIZE]

??are there any stand outs
ie rippers OR to be avoided.
are there any I have missed?

Cheers
Snappytom

PS I am the proud new owner of a K7 plus 70-200 f/2.8 and am looking for something more everyday that is as fast and hardy. I photograph kids' indoor gymnastics and insects legs in the rain on magnificent beaches at sunset!.