after two tries with Sigma 120-300 os I need a canon 300 or 400 which one?

It always depends on the batch as I've found out. I've always been unlucky with 50mm at some point of time, and believe they all came from the same batch. Same thing with 120-300. However, my 70-200 lenses were all great.

Speaking about the Sigma "LOTTERY"

My ticket to the Sigma lottery got me a lens which I can virtually no longer use....

I have a beautiful Sigma 28mm f/1.8 lens which will NOT WORK ON ANY CANON CAMERA LATER THAN THE 10D.

Sigma's reverse engineering required a rechipping of my lens to work with any camera newer than the Canon 10D. However, because Sigma replaced the 28mm f/1.8 lens with a later version. they will not or cannot (amounts to the same thing for me) rechip the lens.

Luckily, I have an obsolete Canon D60 camera which I conveted to full-time infra-red and on which the obsolete Sigma lens will still work!

However, this was my first and very last Sigma lens. Fool me once, shame on you... Fool me twice, Sigma, shame on me!