[OJFord]

I already mentioned 'panels' and container integration.

Idk, I don't know why Tree Style Tab is any more 'standard alternative' (or certainly not that any others are, afaict TST & Sidebery are the most popular two) - they're both extremely popular (Mozilla gives 196k users of TST & 75k of Sidebery; nothing else close) and both 'Recommended' by Mozilla.

Use whatever you want, I did say more than that I just recommend using something to get vertically listed tabs. The tree-ing is a much less big deal to me tbh, though Sidebery does do that too fwiw.