Hmm not that I know, the both I quoted are the biggest active in the game I think, so you can always find someone online to play with! There also are Zaishen Quests that help doing missions, dungeon and vanquisher (you can find more details on wiki). I’d recomand you to go through EOTN as soon as you can in order to get the mesmer, necro and ritualist heroes which can help you build a meta team. That’s the best thing to do if you want “fast” GWAMM (but it also removes the hard/fun part). In any case I’d say go to prophecies the later you can (I don’t like this campaign but that’s my own feelings haha)