You can't go wrong with the OnePlus at it's price point - I have one as my daily driver and love it.
But... it can be a tiny bit glitchy, and it won't be getting Lollipop for many months (assuming it actually does end up getting it). So, there's that.
Unless unlikely revision of N6 price I will concentrate on other models:
OPO but no sd and no removable battery are minuses plus 4G 800MHz band is missing
Note 4 if price reduction
G3 though a bit old already