I've always felt as though I'm unable to fully enjoy RPGs. Final Fantasy is one of my favourite series of games, but outside of that it's pretty limited. Undertale was probably the last RPG I played that I liked, mostly because it did something different with the combat system and the puzzle aspects weren't too over the top. I feel the same way about CrossCode, but I would put that game into a different category as it isn't a traditional RPG.
I just don't want to sink a ton of time into a game that is mostly a grind with story elements and payoffs that are few and far between when I could play a different kind of game that is at least continuously stimulating.
Treasure trove is actually the version I played, I was a bit late on picking up Shovel Knight. I also played Axiom Verge and liked it a lot, but grew tired of trying to figure out where the fuck i was supposed to go. Metroidvania is nice and all, but you forget how frustrating new ones are in comparison to games like Super Metroid where you already have the map memorised.
I have always been bad at Sonic. I think it's something to do with the control that just doesn't click right with me. The speedruns for the first two games are cool, but it's one of those ones like Mega Man where it has a bunch of zips and stuff like that which would turn it into a few months of work to get the game in a place where you could run it competently. I am actually looking for a longish (20-40min) speed game like Mega Man or Sonic to have as my "main game". Everything else I play, maybe with the exception of Contra, is a short run I grind for a week or two and then move onto something new.