I played through Shadowlands and part of Dragonflight and fell off and haven’t played in a long while. Myself and a friend of mine are coming back for MoP remix and also bringing a friend who is new so the 3 of us want to start fresh on a new server and want to know what server would be good for alliance
Look at
https://www.wowprogress.com/realms/rank/us
and sort by Alliance descending.
Stormrage and Sargeras are the biggest Alliance servers, so those are the two I would consider first. The obvious question is whather you would accept the potential downsides of the overcrowded Stormrage, like lag and delays during launches, for the sake of being on the largest server.
Since your character is already on Sargeras, it would seem reasonable to choose that. Just remember you can’t trade or mail Remix characters until Remix ends.