Which browser do you guys recommend?

Firefox when not creating AMP pages and the following excellent HTML free validator:

https://addons.mozilla.org/en-US/firefox...validator/

And Vivaldi for the best AMP Addon validator:

https://chrome.google.com/webstore/detai...mknc?hl=en

Both Addons run in the background, after the page has rendered. Success, warnings and failed result icons are displayed in the toolbar. Also with help and links to relevant errors.