Kindle - had one or another model for many years, but in terms of utility to price ratio, it's still one of the highest. Youtube Premium - I realized I was spending a ton of time on Youtube, both for education, entertainment and podcasts. Removing the annoyance of ads and not being able to just listen to a video while out walking is worth it to me.
Slightly more friendly for sideloading books out the box; Kobo Glo HD Its my favorite gadget. Pretty sure kindle are better value though, and can still be hacked/sideloaded onto. E-Ink is marvel in itself and it is disgustingly uncommon. I hope more products emerge that use them.
unfortunately toying with kindles not trivial, at least not with the latest models. last time I checked, you needed to do some hardware bypassing