I'd love to get away from Chromium based browsers. At the moment I am using Brave.
Is there any other browser that works on and syncs between: MacOS, iPhone / iPad AND Windows? It also has to have adblock capabilities on all of the devices.
FireFox with uBlock Origin would be my first choice but afaik you can't block ads on iPad / iPhone on it.
I was going to suggest Firefox, but TIL Apple doesn't allow non-safari-based browsers and all code must ship through the app store and that's why Firefox iOS doesn't have extension support like it has on Android. Wild.
Thats only because all web browsers on IOS need to use webkit mandated by Apple. However there are legal challenges in the UK claiming that mandatory use of webkit is anti competitive, so IOS may soon have blink/gecko based browsers.
There's no perfect solution with tab/bookmark sync and iOS devices yet. Accepting that, you can have a safer, less frustrating browsing experience on iOS with Safari using 1Blocker.
If you want something similar to libredirect you can use Privacy Redirect - it's $2, not nearly as well executed, and Twitter redirecting broke recently because of the recent changes to their login flow. But it's an option.
For bookmarks I've moved to using Raindrop as a platform-agnostic solution.
Vivaldi is what you're looking for, not sure about their ios support but I know it syncs between android and windows flawlessly and it has it's own built in ad-blocker that you can also install ublock on top of on the desktop but I've never once gotten a popup on mobile just using their ad-blocker, and it blocks a bunch of ads too.
It is based on a chromium fork but they have an extremely strong focus on both privacy and innovation but it isn't one of those browsers that have everything switched on from the get go, they have an amazing set of core features like speed dial (which I can't live without), ad-blocker and a really handy sidebar that contains all the stuff that's usually mooshed into the top bar, however their advanced settings are all opt in so make sure you have a good dig through the settings and turn stuff like mouse gestures on.