I've not played it but I was really enamoured with Persona 5 Stikers as I am with most of these games that take a turn based IP and turn them into action or even Dynasty warriors, like Hyrule Warriors also. They just look like they set out to do exactly what they intended. I never play them but I have to respect them. Also the Persona rythym game, played the Demo, really bold spin off I have no idea if it was good or not cause it's not my thing. Metal Gear Revengence, everyone says it's a great spin off.

I liked Stories 2 a lot. Not played 1

Strikers did well enough. It's a sequel to Persona 5 Vanilla. It plays less like a Warriors game and more just an ARPG version of Persona. Good game.

Oh, Monster Hunter stories is another that looks great. Gotta repect the Japanese for doing these, the closest Western devs going this hard away from the genre is Aloy ending up in Lego. 

Not a spinoff but you may find it funny Geralt and Siri are in Daemon X Machina as skins.

Damn, they look good in that, really cool visual style. The only cross over I tried was the one where they ended up in Monster Hunter. Didn't feel quite right. I was saddened to see Ciri didn't make it into Cyberpunk even though they set it up so perfectly in TW3 when you first meet up with Ciri. 

I still think Mario vs Rabbids is one of the best strategy games made in the last 10 years. Both the original and sequel were superb and great fun. I hope Ubi keeps them coming and maybe we get a Zelda vs Rabbids.

Sword of the Stars: The Pit is a pretty good roguelike spinoff of a 4X series.

Quite a few Mario sports titles could fit that description, too.