Simply a pure Chrome clone with vertical tab bar already is enough to interest me. From my point of view a horizontal tab bar is absurd, making a browser barely usable (I could hardly ever see the tabs captions in Chrome, only comprressed icons, until I've bought a reeeally big display). I feel this way since the days tabs have first been introduced - in Opera on Windows 95 (and it already had vertical tabs bar). Edge has a vertical tabs bar.

Nevertheless I actually use Firefox with a vertical tab extension (there are many) as I find it overall better, also make use of its awesome container tabs (a very nice convenience leap from using multiple browsers for different purposes) and feel nice about using a browser which is kind of (I know it's not really, at least from the financial point of view) independent from privacy&freedom-hostile corporations and actually different from their one technically. Another reason is Edge somehow feels the slowest browser ever to me.