Well... A few years ago I did the same journey, abandoning Firefox for something else. There's several stable and serious browsers out there.
After looking for weeks I created a list of categories... And it depends on what are you willing to sacrifice:
Just want a plain browser, without logins, synchronization, without ANY external connections etc:
Ungoogled-chromium (Windows, Linux...) and Bromite (Android).
Don't care about full web compatibility or speed but keep your privacy under control:
Waterfox Classic and Palemoon (Windows and Linux).
Don't care about Open Source vs Closed Source licensing (but still preserve some privacy):
Vivaldi (the most customizable Chromium-based browser out there but the UI even after several improvements feels a bit slower than other browsers).
Don't care about privacy... Then it's quite easy:
Edge, Chrome, Opera.
If you are into cryptocurrencies or need a nice browser with decent adblocking on iOS: Brave.
I decided to use Vivaldi since I like to personalize the looks of my browser quite a lot.
The best recommendation is to try everything for a while and settle with the one you feel most comfortable.