I cant tell what is the best open face, but I can tell you what is the WORST
Kwon Cheng, marketed in Australia as RXT
I stupidly bought one a while back, crap fit as tight around the forehead and loose elsewhere, uncomfortable as the interior seems to made out of moulded concrete, lifts if going faster than walking pace, synthetic liner makes you sweat, no snap for the chin strap, noisy as buggery, cheaply made.
all in all a real first class shit helmet,
and to top it off there is only one shell size, so a xsl, sl or m have the same shell as a boofhead sized xxlg. so if like me and you noggin is a petite sml or m it looks like a big bulb on your head