You're truly over on The Sweet Setup:

Vivaldi takes a “more is more” view of features, as the defining characteristic of this browser is that it has everything you can think of (and probably more). What makes Vivaldi fundamentally appealing is that you can change almost everything about it, often in ways that you would not expect at all from other browsers.

For example:

Let’s start with something completely unique to Vivaldi that I’ve never, ever seen in another Mac app: menu customization. No, not just a toolbar or some right-click menus, but the literal options that appear in the system menu bar!

Like seriously…an app that lets you customize the system menus! This app ain't for everyone, but if you want to change something about how your browser works, odds are that Vivaldi will let you do it.