Which obscure browser do you daily drive?

The Firefox ToC discussion pushed me down the browser engine rabbit hole (again). Have you had a chance to daily drive some really good but obscure web engine that is not Gecko (Firefox), WebKit (Apple) and Blink (Chromium)? How viable is it for a complete switch - this includes banking, chatting, logging into websites, etc.

Edit: Added link to the Firefox discussion to give better context to my question.