Choosing the right Android browser for has always been about which browser keeps it the most simple, so in that case my daily driver has always been Cromite, and just normal good ol’ Firefox for extensions. But Vivaldi has many features that make me question my line of thinking.
First of all, the tab system that actually mimics desktop browsers is the most useful feature. This means that Vivaldi is probably the number one Android browser for landscape browsing. I know, landscape browsing on a mobile (not a tablet, or a laptop but a *mobile*) is not how most people use their phone browsers, but that is simply because browsers are not optimised for it. But the tab system makes it a lot easier to view it this way if one chooses to.
The sync system for Vivaldi is also a first-class feature, not for syncing tabs (which other browsers easily do) but because Vivaldi has added other features such as note taking. Note taking syncs seamlessly and immediately between PC and phone. If I need to jot something down on the PC, so I can download it on my Android later, I just copy/paste the URL and it appears in the Android browser in no time.
So Vivaldi is more feature rich and being a Chromium based browser, does not use as much battery as Firefox based browsers do on Android. It might just become a daily Android driver one day in the future for me.