It will probably be Opera. The only reason I don't use their browsers is because I don't like running non-free software and really don't like using it heavily or for anything important but losing ad block would push me into it.
But they have built-in crypto ads too that so far you can disable.
I think the problem is. What if Chromium won't have code supporting V2 anymore? This means, it is just impossible to run V2 extensions because V2 is not only turned off but completely removed.
Vivaldi seems to have decided that they will provide a built-in feature for advanced ad blocking and Edge seems to be undecided yet.
[0]: https://forum.vivaldi.net/topic/98631/manifest-v3-update-viv...
[1]: https://github.com/MicrosoftDocs/edge-developer/blob/main/mi...
If you want to go back to the "original Opera", that is now Vivaldi.
Vivaldi already has a built-in adblocker in place, so Vivaldi ad-blocking doesn't depend on V2 being available.
This said, V2 shouldn't be removed at all because this will stifle the extension ecosystem. I predict that extensions will stagnate. Just because some ad-obsessed company killed V2 to stop an extension threatening their revenue.