I'm using the OEM heated grips. Expensive but plug and play electrics, nice attention to detail (the heat controller bracket is rubber mounted and attaches within easy reach on the mirror stem), and they get very hot. Some people have commented that the left side doesn't stay as hot as the right because the bare handlebar drains away the heat. I insulated the bar with heat shrink tubing before installing the left grip and both sides heat evenly.
2014 350 EXC-F
2006 Djebel 250XC