I've been renting AIQ Pro for almost two months, and I've only playted Sth Prem on location with UV kit, but I've played it quite a bit.
My non-pinball family prefers Sth by a mile. It's approachable, the shots are pretty clear and it has some fun things. I'm not a rules expert on it, but it's pretty understandable on it's own after awhile. I don't find it particularly fun to shoot and there are several bits that annoy me. I don't like the right shot to the pops at all. I don't like the saucer on the left. It just doesn't feel great. It's a solid game that other people love, but it feels clunky at times to me and none of the shots really feel awesome to make.
I had to watch a tutorial on AIQ to really understand the game, but it's actually also very straightforward to 'just play', with thousands of strategies you can employ for scoring if you're good enough. The combo possibilities on AIQ are very, very fun for me. The feed from the Captain Marvel shot is kinda dicey as is out of the pops at times. Outside of that, it's fun to shoot.
As a 'just ok' pinball player, something about AIQ isn't "super fun" and I can't quite put my finger on what it is. I will play it, and sometimes I'll have very good games. But, it never calls me to play it like other games. There's just something about the way the rules are structured (I think) that doesn't hit that reward center of the brain for me that I ever really feel accomplished or SO CLOSE that I want to play again. It's just flat. The only sense of excitement or tension is in the Hulk gamma ray shot and it's not even worth shooting that 99% of the time. Soul Gem tension could be ratched up for a better experience as could the tension in all the modes when you get close to finishing them. With a few tweaks, it could be pretty addictive.
For me, neither game would have a permanent home with me. I've had fun learning and shooting AIQ, but I'm not extending my rental past two months. A really good game on AIQ can easily take an hour. However, most games are done in about a minute. It's the brutalist easy to shoot game I've ever seen.
If I had to pick from the two sitting next to each other at a bar, and I only could play one, one time. It'd be Stranger Things all day. I'm more likely to have a fun game and experience the same stuff. At home on free play where I can explore and take my time, I'd take AIQ.