[davidmanze]

All three lenses are Sigma Art types. And less or more elements - it also counts how large these are, I think.

135 Specs

105 specs

85 specs

The Otus has 14/11 lenses/groups

    Much as I had my doubts about the AF accuracy of the earlier Art lenses .... the images that come out of them is inarguable .....
 .... the more recent art glass seems to have refined the AF performance to OEM levels of accuracy and most of the problems have disappeared ..... along with the complaints in the forums.

   I have no desperate use for it ....... but the 105mm F1.4 portrait lens looks like a dream optic ...... and considerably more affordable than the Nikkor version.

[JJ_SO]

Browsing through Sigma's current lineup of firmware, there's no lens without a firmware version*, and no firmware  (for lenses) older than 2018 - they really do care, and they also improve, especially on the Canon side of things. I just remember the fuzz and the long absence of the 300/4 PF E because of the bad VR unit. The dock and the firmware policy is one of Sigma's smartest moves.

Tamron copied that but is not up to the task. I'm about to sell the 100-400 and get the Sigma version instead. These lenses are simply practical to carry and good enough for my needs - both of them. It just so happens that the Tamron is working on the old mirrorless 1 V2, but not on the new Z 7. Sorry for the off-topic.

*correction: The new 40 and 28 f/1.4 are version 1.00