So I picked up a couple of suggested ones since making this post and have given them all about an hour or two of play.
Mechanicus is the absolute tits. Love my squad of weird little tech priests that I've started naming Rush references. I'll probably grab Chaos Gate: Daemonhunters when I finish, for a different take on "XCOM 40k".
Inquisitor - Martyr: Diablo-style 40k is great so far, even if it could explain some things in-game better. I started with a tech-priest here too, I think the AdMech are my favorite dudes in this universe. But then I found out tech priest skips Martyr and goes straight into Prophecy, apparently? So I rolled up a Sister of Battle to go through the original campaign first.
Boltgun: One review tagline I saw called it the best 1994 shooter in 2023, and that's pretty much accurate. Good soundtrack on this one too. It's as nostalgic as playing Doom 2, yet buttery smooth.
Space Marine 1 is the one I've played least so far. It seems very solid, I'll probably be more excited about it when I get a chainsword to replace this big weird knife. I might need to get a helmet mod, it's killing me to see this dude running around in full armor with his meat head exposed.