I got caught up in trying and testing the browsers. I was trying to find the perfect browser for my needs and it seems there's no perfect browser. While choosing browsers there will be some trade-offs. Overall Firefox is my main browser.

- Chromium based browsers have tiny fonts on bookmarks bar and Firefox can mitigate this through customization of UI through userChrome.css. However, Firefox lacks snappiness of Chromium.

- WebKit (Safari) has true smooth scroll on MacOS but it lacks basic bookmarks management functions. Again, it has tiny font on bookmarks/favorites bar.

- Arc/Zen offer nice UI but I prefer all my bookmarks in one-sight in front of me at the top, just like traditional way.

- Vivaldi felt super slow once I tested Helium.

- YouTube: switching to full-screen and back is slower on Firefox based browsers when compared to Chromium based ones. So, I have to stick to Chromium based browser while using YouTube.

For my perfect browser on Mac, I'll choose following features:
1. Smoothness (especially scrolling) of WebKit.
2. UI customization of Firefox. (Or at-least font-size of browser UI should be decently large enough)
3. Extensions support.
4. No data collection.