It's no secret that I like STABmons better, even after playing Sketch seriously over the duration of OMPL. I like it better for lots of reasons which don't really matter since this isn't an objective debate.
The reason that I care so much is that it frustrates me to put a lot of effort into a metagame only to have it labeled as "dead". I put a lot into STABmons over the last few years: consistently updating the VR, offering unsolicited teambuilding help to newer players on ladder, compiling a list of viable moves so that people might stop running Night Daze (please stop, it's worse than Dark Pulse), RMT-ing my best team, and contributing to discussion on the metagame whenever it popped up in chat. I think there's a large psychological component to a ladder's activity, in that if people assume they're not going to find a game and meet even slight resistance, then they stop trying and their assumption becomes true. Obviously there are some real interest issues as well (I'm not delusional, I swear).
I'll address what seems to be people's primary complaint about STABmons first. FakeSpeed is very powerful. There's no denying that. However, this gen its checks got significantly better (as evidenced by Diggersby and Porygon-Z still being in the metagame in a reasonably balanced way). Beak Blast, Strength Sap, Shore Up, Celesteela, Toxapex, and Buzzwole are all phenomenal new tools for checking Physical mons in general. If you feel like you "need" to run Defensive Landorus-T on every team to stop FakeSpeeders, then I would encourage you to try out Celesteela, Garchomp, Ferrothorn, Toxapex, M-Venusaur, Buzzwole, Tangrowth, Steelix, Rotom-X, Gyarados, Tapu Fini, M-Scizor, Rhydon, Porygon2, Slowbro, or even something less "traditional", like Zapdos, Celebi, Mew, Mandibuzz, Slowking, Umbreon, Hippowdon, Jirachi, or defensive Bewear. I promise you, as someone who plays (very) Fat Balance and Semistall, that defensive counterplay is massive. Offensive counterplay is obviously a bit harder since we're talking about strong priority, but Excadrill, Alakazam, Aerodactyl, Gengar, M-Lopunny, Magearna, Heatran, Bewear, Mimikyu, Terrakion and a number of others are all fit for the task. As with any blanket strategy you're trying to beat (think rain), there is no one-size-fits-all counter that can tank any hit from +2 Diggs, +2 Lopunny, and mixed Porygon-Z, while OHKO'ing back, so carrying a few pokemon from this long list is pretty important. Luckily the list is extremely long. A longer list can be found in the second post
here.
All that said, I would prefer to have OMotM every few months, or a rotational ladder every fewer months, than a permanent one if people's perception is that it would be "dead". I certainly don't want people to resent STABmons.