You can also go down the rabbit hole by searching “best boomboxes” and you will open the Pandora box

But I’d do a point system and go from there, here are some categories:
What generation?
Chrome or black plastic?
One piece vs three pieces?
Looks or sound quality?
Sliders?
Portability and size?
Weak points like lousy switches/pots/sliders/speakers
Budget?
Do you have someone to help or will you try to restore?
For example, the Toshiba RT-S90 is said by some to be a top box but it in my experience it has a lousy build, is difficult to fix and sound isn’t that great. The m70 can be a safer choice but it can have problems with sliders so if you don’t like sliders, there are other models.
There are lots of threads, I would read up for a few weeks before making a target list. If you can meet someone to see and hear boxes in person, that’s the best option. But be careful because if you get to hear a JVC m90 or a PC 55, your jaw may just drop and your brain will be hijacked so make sure you brace first.