If the alternatives are store forever, throw in the trash, or give to a carrier...
Nobody is getting the data off at my house. I assume nobody will go through the dump looking for old phones, but someone did go through the dump and found the ET cartridges, so there's prescedent. Also, I feel a little bad about putting phones directly in the dump.
If it goes to a carrier program, there's a good chance it goes into a repair process where the battery is replaced and maybe it works again. If it works again, I expect it to get the least intensive wipe required so that the user can get into the home screen, and then sold. That might mean the new user can get access to my data.
Story time: my spouse had an Amazon Fire phone for quite some time; when she was done with it, my dad needed a phone, but FireOS was a really poor choice, so I flashed it with a 3rd party Android build. Several years later, he ran it all the way out of battery, and when he got it charged up, somehow it booted up into FireOS instead and had my spouse's accounts and what not. Whoops. No big deal, we got him a new phone and got the Fire Phone back (and I tried to wipe it again, but better) and now it lives in a drawer and won't power on.