Time to destroy this mountain of woe. What do I keep (that can be built in a year) for the most variety?

I have a consumerism problem that I have been slowly working on. In 2020 I got really into Warhammer thanks to YouTube. I bought a lot since there wasn't much else one could do. In 2021 I went to the US Opens in the US, doing fairly well for my first time playing AoS going 3-2, 4-1 (that one being me forfeiting before the game started due to my opponent's behavior), and 4-1. I got really into display painting, played in my local league, fell into the FOMO box trap, and generally thought this hobby was going to be my main thing. 2023 I went to Warhammer Fest and luckily since I had the little Golden Throne pass I did not have the crappy experience may reported on YouTube. I also did Adepticon that year and took all the paint classes, too many really as I was in class from 8am to 11pm and eventually things just stop sticking.

I was starting to feel the burnout and getting pretty overwhelmed by my growing backlog. Yes, I recognize I put myself in this position. After buying Leviathan I decided I was ready to do something about it and for the most part cut off buying any more models. I am not sure when that cutoff was, but I know for sure I didn't buy a single model last year. That stemmed the tide a bit, but didn't solve the problem I created. This year I intend to go drastic and get rid of a good chunk of this. I pulled it all out from the various areas it was spread out and when it is all together like this, it is sort of sad. Just wasted potential I guess, my fellow gifted kids know what that is like, right? So I sorted this into keep and get rid of sections. Everything to the right of the Underworlds boxes is being gotten rid of. However that still leaves a ton to the left of the Underworlds boxes and as you can see, almost all of this except the left most piles is unopened. I have a bunch of kits I thought I was going to immediately build, took out of the box and flattened it, and then built one dude to paint and put the sprues in a box or drawer.

First world problems I know, I am judging myself pretty harshly, enough for the both of us. This is where I need the community's help. I am setting a hard deadline for myself that anything not built by the end of the year has to go. Since I build for painting, I am pretty meticulous in the build process so I am slow. Getting rid of 1/3rd of my backlog is not enough, I probably need closer to 3/4ths. My question is, what should I focus on so that I can have the most variety of play? Would it be better to make a giant army of something like Space Marines and Stormcasts that have so many different units I could rotate lists in the same army? Should I focus on multiple armies but smaller game modes like Combat Patrol and Spearhead? Do I go even smaller and just do skirmish level games? My end goal is for my board gaming friends to be able to come over, pick what looks cool off the shelf, and roll some dice a few times a month without things getting too samey. I think I am done with the competitive scene, so keeping a high level army is not really necessary anymore (and if I am being honest, meta chasing is partly why I am in this situation).