I am gradually working through the lens reviews so patience is required
Have to use them enough to come to conclusions about the performance
My video review is here:https://www.youtube.com/watch?v=oEt7UL5-bpE
Conclusions are in short solid zoom lens which will work best for FF users, though it holds up pretty well on APS-C if you can live with the 42mm equivalent at the wide end.
The lens surprised me in a few ways it's usable wide open at the top end, albeit with a bit less contrast. It's pretty consistent across the range and stopped down a bit resolution is very good.
V the 24-105mm my thoughts are simple both lenses are quite sharp that is not the issue neither disappoints (price relative to performance of course). The 28-105mm has less vignetting, less distortion (still has some tele end not quite as much as the 24-105mm), better flare control, less CA by quite some margin and it's just easier to work with ie less post processing tweaking - but it's a bit heavier than the 24-105mm and not quite as small (both are compact lenses)
I would consider it as a very fine choice for a standard lens on 35mm. I know the Tamron 24-70mm G2 isn't on A mount - the previous one is, however it's just too damn heavy for me as a normal lens. I'd rather bag a faster prime for low light and save lugging it around. On crop situation is different a lens like the Tamron 17-50mm is quite light and small you don't feel it. Is 28mm wide enough? Well 24mm is nice at times for most uses I'd say it is. Add a 100-200mm F4.5 and you have a 2 lens landscape kit which takes up little space in the bag.
I have more lenses to look at this one is a keeper IMO. If you are on full frame and can get a good copy it's a bargain