What spec is the most efficient / fastest to do t8+ delves on?

Well that is the question.

To clarify:

- in general

- depening on gear

- 606 ret/prot pala vs. 600ish bear/moonkin (these are the actual chars I do have)

And t8+ is the minimum. I still need to do t10 and t11. Which of my classes would be best to solo this - or do I just search a group as a tank. And if so, which delve is the easiest for this?

EDIT: did t10 and 11 delves easily as 610 prot pala. fungal fully, 31 bran heal. explose spores into mobs = dmg.

EDITT: also did zevkir ?? and his 3 archievments. took 15-20 tries as 612 ret.