Favourite Pair of Sith

Same.

^Both are badass

Too hard, too many great pairs.

Revan/Malak

Bane/Zannah

Plagueis/Sidious

Sidious/Dooku

Sidious/Vader

^Yeah, those first 2 pairs you mentioned are honourable mentions

Durp I expected you to pick Bane and Zannah, given they're your favourite Sith after Vader

If I had to choose 1 I would lean closer to Bane and Zannah, but all of the ones I listed have interesting dynamics, and context to their work, and I enjoy greatly. The great thing about the Sith is the masters almost completely shape the relationship, so you always get unique takes on the duo depending how the master sees and views things. Wish the rule of 2 era was more fleshed out we only see the first generation go, and then the tail end of it, with small bits in the middle. We probably could have a lot more great duos if it was more explored.

I also forgot to list Exar Kun and Ulic Qu-droma, they were another great pair.

LT same

Vader and Sidious were the OG.