1. Safari iOS
2. Firefox
3. Chrome / Chrome Android
4. IE11 / IE11 Metro
I only curse IE9/IE10 when they don't support a moden feature, but I don't mind using display:table instead of flexbox (to name an example) as long as it gets the work done in IE9/IE10.Although I don't bother testing IE10- to be honest, I just blindly trust the document modes of IE11, I'd rather spend time testing different mobile devices than testing different IE versions.
PS. I might be biased in the sense that I have been doing web development since like 15 years ago, and I'm already accustomed to the broken box model of IE. With Firefox I literally have to ask myself every time "what the f%@k did I do wrong???", but with IE literally is "oh you silly IE, I just have to set X and Y extra attributes and it's done".