I think the Acer c720 probably accounts for 30% of all Chromebooks sold, i.e. its the #1 seller. It is very compact, has a great set of ports, and the fastest CPU of any Chromebook (Celeron 2955U and i3-4005, both are the fastest in their class). On amazon the c720 is the #4 selling laptop.
Most of the Chromebooks this year have a SIGNIFICANTLY slower processor, the N2840, a 4-cpu ATOM processor, which is about 25%-40% slower than the Celeron 2955U. See www.passmark.com for full details.