Honorable mentions:
There are many other good factions in pro wrestling. SCU has been a staple in both ROH and now AEW. They are respected veterans who are good on the mic and in the ring. Christopher Daniels finally won the ROH World title two years ago after having never won it.
Still a part of ROH is the Kingdom. While I'm not personally a huge fan of any of the members, Matt Taven has remained loyal to the company for over seven years. The first iteration was better as it included Mike Bennett, Maria Kanellis and Cole. Taven is clearly the top member of that group. It has held the ROH Six-Man Tag Team titles and Taven is the current ROH World Champion.
The Hart Foundation and the Dynasty have primarily been battling each other over the last year in MLW. The Hart Foundation initially came across as cocky heels late last year, but like other groups including the NWO and the Bullet Club, they were so popular that the became de facto faced. Teddy Hart's in-ring game and the contributions of Davey Boy Smith Jr. and Brian Pillman Jr. have made them a top group in MLW.
Hart has held the Middleweight Championship since late last year whereas the group also won the Tag Team titles from the Lucha Brothers. In turn, they dropped the belts to the Dynasty, headed by MJF. The shelf life of that group might be shorter than many other factions due to AEW's show starting on October 2nd. He'll likely have to finish up with MLW before that happens.
Alexander Hammerstone is someone that Vince McMahon would love in the WWE and he's the promotion's current Openweight Champ. The Rascalz, like OVE, all came from Combat Zone Wrestling. They've put on some insane matches and their promos are entertaining if you liked That 70s Show. They're all pretty young but have a bright future in the industry.
Lifeblood was formed earlier this year by Juice Robinson. He felt that ROH had lost some of what it was founded on, including respect for the ring and the opponent. He's been mainly involved in NJPW but Williams, Haskins and Bandido have routinely stolen the show in most of their matches.
Promociones Dorado is a focal point of MLW but it was at its height with Low Ki as both a member and MLW Champion. It's still going strong with L.A. Park, El Hijo de L.A. Park and Ricky Martinez, but it isn't as formidable.
Imperium was primarily formed around Walter after he became the NXT UK Champion. He was treated like a big deal as he was the one to end Pete Dunne's record-setting title reign. Fabian Aichner and Marcel Barthel are an underrated tag team and it's a little surprising that they haven't had a tag title shot. And Alexander Wolfe left one faction in Sanity for another one.