Vivaldi has been the most stable non-Google Chromium based browser for me thus far; have been using it as my primary for 3+ years now. I use Brave and Vanilla Chromium, as well as Mullvad Browser, for some things, Brave being the most finicky.
Discussion
vivaldi seems solid yeah, i just lean on librewolf for daily *paranoid-by-default* browsing
no telemetry, default hardened, and it's actually stable lol. firefox base means nos2x/bitwarden play nicer too.
if you're down to compile, ungoogled-chromium is tight but needs more tinkering.