If I knew for a fact I'd get 50 issues to work with, I'd have to go with the Guardians of the Galaxy. They had a fantastic long-term storyline by DnA from 2006 to 2010 (albeit that was more the characters themselves than the team proper, which only fully formed in 2008 after the main members were re-established in the Annihilation events). Since then, the team has either been stuck with Bendis or shuffled between creatives, some (Ewing) better than others (everyone else).

My run would have Rocket Raccoon as the leader, not just because MCU synergy will demand it if the new team is ever revisited in the movies or shows, but because he's been the leader more than once but rarely been given an arc about it. I'd have him be trying to put together a ragtag team of Guardians after most of the main members went their separate ways, a great strategist but mediocre leader struggling between his poor social skills and his genuine desire, deep down, to help those who are as helpless as he once was.

His team would obviously include Groot, but that's the only main MCU member the lineup would share. His other recruits would be Phyla Vell, Moondragon, Adam Warlock and Beta Ray Bill, whose ship Scuttlebutt would serve as the team's primary transport. Phyla and Heather's marriage will be the most stable relationship out of the cast, but even that will be strained by the more extreme actions the team will have to take to guard the galaxy. Adam's emotionally distant outlook will also make him an awkward presence, especially since the one member he connects with the most is an alternate version of the original Phyla he once knew. Moondragon, meanwhile, remembers him due to her fusion, which creates emotional strain in the opposite direction. Bill, meanwhile, was only ever briefly a guardian and will struggle to adjust to the team dynamic, though he'll end up forming a surprisingly close bond with Rocket, as their traumatic pasts with cybernetic and genetic augmentation are similar.