Who should continue the story Michael's group or El's group?
if you could only choose one set of cast who would you pick?
I don't think you could do it that way. You'd be leaving essential characters behind with either choice and pretty much gut the show. Plus, no matter what happens, or how crazy the last two seasons get, there's one fan wish they absolutely must grant: a happy ending for Mike and El.
sharebittersweet endings is the way it works
shareHappy endings are relative. There will be more main character deaths, especially near the end, so even the ones who make it pay a price. If they do a King inspired ending we'll probably see an epilogue segment set years later where the survivors gather for some occasion and we get to see what they've been up to, meet their kids, etc. It would be nice to see Mike and Eleven still together and happy.
If I were writing it, that would also set up a neat final scene where their own young daughter goes off by herself into the woods, sits down on the ground and concentrates hard, then we see a mini-gate open in the air over her outstretched palm, tiny - maybe an inch across - and she speaks to it: "It's okay, we're alone now." The Mind Flayer may be gone but who knows what else is out there? Is this thing she's made contact with friendly, or a new threat? We're left to wonder as the credits roll.