Sidebery has a form of Tab Groups called panels (see: https://imgur.com/Za9lwej) that are built into the functionality. I also have just found Sidebery to work a little better than any of the alternatives. But they're not too far apart.

TST is a hierarchy as well, so you can have children, and you can create groups (folders) too

(Not trying to crap on Sidebery at all; just checking the differences :)

Edit: Oh, are you referring to those icons at the very top of the tabs? If so, that is sort of neat indeed

Yes lots... Container integration... So certain urls always open in certain container... Snapshots

I moved from tst a few years ago.. Let me get rid of a few more extensions too