tamron vs sigma

probably not a new thread ,if not i apologise. new to this side of computer use. any way my tamron 18-250 is kaput. i am thinking about a tamron 70-300 Di LD MACRO 1:2 a
sigma 70-300 DG MACRO or a
sigma 70-300 APO DG MACRO
i know low budget end, but needs must at the present time. any advice which one to go with much appreciated
Pentax K7, Sigma 105 MACRO, Pentax 10-17 Fisheye,Pentax 16-45,Pentax 50 1.7,Teleplus2x converter

I have a Sigma 70-300 APO DG Macro and I think it is excellent for the money (IMO) - in good light when stopped down to f8/9 it is commendably sharp, and the macro function is useful although I do sometimes find it tricky to switch it back to 'normal' from 'macro' using the little switch on the side of the lens... leads to a bit of faff but otherwise I would recommend it for the price. I am afraid I have no experience with the other two... It's also quite light and compact than other lenses which go out to 300mm which might also be a factor.

Regards

Why not a pentax 55-300 ?
The DAL version is almost the same price as the non APO sigma you don't have a hood though...

If budget is limited then I'd personally get the Tamron 70-300, from my own experiences it's sharper than the Sigma, although it does suffer purple fringing.

If budget is a little more flexible then without doubt the Pentax DA 55-300 is the best consumer zoom available at the moment - it has the sharpness of the Tamron without PF and nicer colour/contrast rendition

Simon