I probably would have said MP if you had asked me this during the 7th and early 8th gen of consoles (plus when I had great friend groups to play with back then). Around 2017 or so I'd say SP now.

Multiplayer avoids me :(

I've been playing 80-90 % single-player for the last 5 years or so and most of my favorite games are single-player with a few exceptions, but I am kind of starting to value multiplayer a bit higher again (it was also the main thing I played a decade ago). I'll keep playing a mix of both I'm sure, but I find with single-player games I only want to spend time on it these days if it's quite unique or quite good.

I prefer a really good MP still to this day, but those are rare for me. Destiny was my go to when it launched but didn't really live up to the expectations and lost much of my interest well before Destiny 2 launched. I don't play it much anymore. Rainbow Six Siege has been my go to since it came out but it's not quite as compelling as it used to be with the changes they've made over the years.
The most recent SP games have been Death Stranding, Days Gone, Ghost Runner and Superhot. All were really good. I'm going to start Callisto Protocol soon.

muliplayer is more fun, but i perfer single player games because they are not as addicting and you will be stuck playing one game for ages if it's really good.