I use Bing on my desktop, google on my phone. I use Bing to earn credits for free stuff, plus it seems to be better for searching for Windows-type stuff.
Duckduckgo is good, but I haven't felt the need to move from Google. I've gave up caring about Google having all our information. They make good services.
Google because it syncs stuff between my PCs in Chrome. IE if I search Ark A it knows what to bring up. Also is pretty smart about knowing what I want easily.