Anybody using either of the above makes?I would be interested to hear what people think of them(image quality etc).
Regards Steve

I used a Tamron 80-210mm zoom on an Olympus OM10 SLR for about 20 years and found the quality to be thoroughly excellent.
It was comparable to Olympus own-brand lenses in quality, but considerably cheaper.
I haven't bought lenses for a while but Tamron are very highly regarded (similar to Sigma in quality) and have been around a long time; Tokina are usually less expensive but in the tests I've seen generally of a fairly high quality.