I'd like to see it use something other than chromium.

The Firefox fork Zen is what I use now and it really covers everything I want, which is a nice looking browser with ublock origin, container tabs, and no extra features like AI or Pocket or whatever other annoying addon seems to be crammed into everything else.

Reliable and encrypted sync is important. One frustration I do have with Firefox is sync doesn't sync everything, certain settings don't sync, and about:config tweaks don't either.

Zero telemetry is also important, as is having a home tab that doesn't connect to anything externally by default. Ideally other than checking for updates on addons and sync, there should be 0 connections made until a website is visited.

Overall I just want a solid browser that lets me read web pages.