Safari at the moment but thinking about going to Firefox

I switched from Chrome to Brave a few months ago. https://www.brave.com/

I attempted it but extension support is not especially user-friendly.

I would recommend Vivaldi as it supports Chrome extensions. Chrome apps can be installed, but not used (hopefully Vivaldi fixes that).

I really like the idea of Brave, but not having extension support is a major hurdle which I hope they get over.

I'm currently using Vivaldi, but have to say that it's not really an ideal analogue of Chrome as it doesn't carry over some of the everyday features and affordances of Chrome. That's partly understandable, because it's actually (apparently) intended to be a browser for Opera users to migrate to. It's also a bit buggy.

I'm surprised there isn't a straightforward and user-friendly Google-less Chromium browser available.

I 100% agree with your statement, but I feel that Vivaldi is currently the best browser that's close to Chrome in terms of feature parity. Hopefully though, with more support, they will become an efficient browser that's unique enough to be separate from Chrome but have the features we know and love.

Been using Brave on mobile and it's great, but the UI layout on desktop is awkward so I don't use it there.

Anecdotally I'm in the same boat. I use Firefox at work on Linux, but at home (on MacOS) Safari works/looks/feels better than Firefox.

Firefox on Android is vastly superior experience due to one simple thing - extensions. microBlock origin makes web actually usable again on mobile platforms.

Yes, yes and yes. Though some extensions do not work, uBlock works and it's a life savior.

Firefox 57/Nightly! Do it.

I moved from firefox to opera