I didn't think the Wax & Wayne books were nearly as good as the Mistborn books. They are not really part of the Mistborn story. They take place in the same world 200 years later (or something like that). There are a few callbacks to the trilogy, but mostly it's its own thing. Waxillium is kinda dull (he's a worse Elend in every way), but Wayne is a lot of fun. None of the stories excited me at all, even after reading the short story and learning the "one more secret."

I don't regret reading them though and I wouldn't tell someone else to not read them. Just that the quality is not the same.

You still have the third Mistborn to read and while it's not the best, it has a great ending that wraps everything up well. I loved the ending, and I can't say that as much as I'd like to.

It's not Mistborn but it's similar, the relatively new Hierarchy series is kinda similar to Mistborn, but with the magic system toned way down. The first book The Will of the Many came out a year or two ago, and the second one, The Strength of the Few, just came out. I think there are going to be three? Maybe four? It's kinda like if Harry Potter were set in Roman times. They have magic, but it's Roman themed and it's based on Will being ceded from people below you. If you're at the bottom, you get none, but you give up like a third to half of your willpower each day to the person above you. They have Will-powered airships, traps, devices, but no big explosive/bombastic magic, per se. And the first book was just twist after twist. Lots of fun to read.

Other than that, I'd tentatively recommend the Silo series by Hugh Howey, though the Apple TV series is kind of rewriting them, with the author's blessing. The books were good (there are 3 of them, so the series is done) but they were kinda rushed and it's nice that Apple is letting him revisit and revise his story in the series, which is very much worth watching. The series may be better because he's constantly improving his story, but the books are not bad at all. It's kind of like Fallout if they never left the Vault (called a Silo in this case), and it's much bigger, something like 150 storeys underground, with each level having many homes and businesses. In fact, most people only ever go up or down a few storeys in their lifetime because they don't have to go farther to get all they need. The story commonly refers to the big cafeteria/meeting place on the first floor, but ostensibly they would have a place like that every 5-10 floors. Things like that, and a Sheriff responsible for all 150, are things that don't quite add up — if he/she and others can go up and down all 150, why don't more people? "Just because"? Either way, it's still a fun little puzzle to get through.