NZXT's H1 v2 is one of my favourite small form factor PC cases, but a high price point (and a manufacturing defect in the V1 model) kept it from seeing widespread adoption. It's now possible to pick up this Mini ITX case from Best Buy for $200, half its usual price and a good deal for a case that includes a 750W SFX power supply, 140mm AiO and top fan.
I've actually got an NZXT H1 v2 here at Digital Foundry's Bristol HQ, and it's a cracking little case. I keep it next to my TV downstairs, where it serves as a high-powered media server and couch gaming machine. You can fit surprisingly high-grade components inside - I've fit an Asus ROG Strix RTX 3090 in there, with two-slot GPUs up to 324mm long and 58mm thick supported.
Installation is super straightforward too, with basically all of the fiddly bits preinstalled. All you need to do is get your Mini ITX motherboard, install your CPU, RAM and storage onto it, then place it inside the case, screw down the AiO cooler and plug in a few cables. From there, the only remaining task is slotting in your graphics card, which is easy thanks to the removable panels on every face, plugging in its power and turning the whole unit on. Not having to deal with AiO configuration, fan placement and routing PSU cables is honestly a blessing.
Once assembled, the NZXT H1 v2 looks great and performs well. The glass front panel isn't the best for thermals, but the bottom to top cooling works well and I didn't see any thermal throttling even with relatively high-end components. The top I/O panel is conveniently located, with the rear I/O panel underneath the unit and therefore a little trickier to get to - but this does at least provide a tidy look.
Overall, it's worth looking at some reviews and considering this option if you're in the market for a small form factor case. There are smaller and cheaper options available, but this NZXT case is a great combination of style, usability and performance.