I've been in numerous poorly built apartments and the only effective way I ever found to mask doors/cabinets slamming, footsteps etc. was with a portable hose AC unit. The compressor was loud and generated a nice masking low frequency tone making it harder to hear that nonsense. It took a week to adjust to the sound, but after that it was quite soothing. Of course this isn't actually solving anything, it's just driving up the noise floor for low frequency and contributing to making everything louder.

Unfortunately they're heavy, woefully inefficient, and quite expensive to run.

I later moved into a newly built "luxury" apartment where the neighbors garage was directly under my bedroom. I figured as long as I got a decent neighbor it wouldn't be too bad. Struck out and got someone underemployed driving a 2 fast 2 furious civic with custom exhaust. Shook the entire building every night between 12 and 4 AM. No way to mask that. Lesson learned.

Top floor always, corner if you can, never directly above or next to a garage. Only exception is if the building is made out of concrete, which is exceptionally rare and will cost more. More expensive place the better -- you have a (slightly) higher chance of getting next to working professionals and quiet families.