Firefox is my default because of the widespread compatibility and the extensions. It's terrible as a touch browser though with bad scrolling.
My secondary browser is Edge. The rendering is great when it works right and the touch is very good (though Modern IE for Windows 8.1 is still better as a touch browser). A lot of the roughness of Edge is going away which is a good thing (finally, stuff like in-browser PDF controls are there). And the web notes and sharing features are useful. It only needs better compatibility, and extensions support. Even the forums on Windows Central are awful with Edge (sluggish response including typing text).
I refuse to use Chrome. Google wants to play hardball and gives an FU to Microsoft? Well, I'll give them an FU back. When Google decides to give feature parity to Windows users, then I'll consider them again. Heck, Chrome in ChromeOS is better than Chrome in Windows.
I refuse to use Chrome as in my experience it has two major flaws. Security (plain awful) and battery drain.
Google in general is dropping the ball if looking at what they have been doing with Google+,Photo's, Storage space and Gmail Inbox. It's a mess. I have escaped the Google limitations with a local 1 TB free online storage solution, Flickr for Photo's ( 1 TB Yahoo account), Outlook (30 Gb free plan) for mail.
I hate how Gmail uses Google Drive space (15GB). Every 6 months, I have to download and clear emails from my dad's account for him because he's constantly running out of space due to emails. He's not caving in to the storage upgrade pricing. Once you hit the limit, Gmail refuses to accept any more incoming emails. And if you start deleting too many emails within a short amount of time, they lock the account due to "suspicious behavior."