Hi!
I'm mostly a 50mil shooter (95% of my shots)
The more tele I went to is a 135mm which is a gorgeous focal lens.
But then, I wanted to make birds picture of my garden with my son. Si I got a second hand 100 400 sigma, which is a nice compromise for a tele, not too expensive, not too heavy, and still 400mm.
But then I had the surprise to use it for landscape first, after a beautiful storm at home.
I have the Sigma 100-400 and like it a lot. It is big and heavy for longer trips by foot but I like the images I get from it. I tend to use tele lenses for landscape photos because I can pick out details without walking long ways to the right spot for a photo with a shorter lens.
I have been a big fan of this lens and purchased it when it first came out. I am a landscape photographer and my 24-105 is the lens that has delivered the largest number of images, closely followed by the Sigma. I can't compare it to the Tamron other than just preferring the build quality of Sigma in general to that of Tamron based upon my ownership of the 70-180.
