Campaign 1: Vox Machina

"Vox Machina is the first campaign that Critical Role started with. However, it’s also one of the hardest ones to understand at first given that it starts off right where they were in the middle of their home game. There are some fans who do recommend that you start off in some of the later episodes, specifically after Orion Acaba left the show at episode 27.

There’s a whole host of reasons why this is recommended, notably that the cast tends to be a lot more comfortable from this point on and the story is pretty easy to pick up from that point and onwards. I, personally, believe that Vox Machina is the essential campaign to start from given that it’s, truly, a tried and true Dungeons & Dragons story of intrepid adventurers coming into their own and growing in strength and power.

Vox Machina provides a solid foundation that will allow you to appreciate the other campaigns all the more. Plus, it will allow you to get a good grasp on the cast and grow endeared with their antics all the more.

If you have Prime Video, you can skip over a good portion of the first campaign by watching The Legend of Vox Machina. It follows the streamed campaign’s story almost exactly, lending you a solid grasp on the characters (and what they look like), and it eases you into the story in a way that isn’t as jarring as the actual stream."

—https://www.thegamer.com/critical-role-how-to-watch/