Both Fire % and CHC for amulet. But I am not be an expert . So if you can't get Both stats I would go with CHC 6% . Then you must Get Fire % on Bracers fore sure and hopefully another 6% CHC on Bracers.
Is the priority on most amulets for DPS (non-thorns, non-MH, both of which do not affect monk). You always want socket, CHC, and CHD; fire% is awesome to get but oftentimes you have to settle for main stat because it's hard to get all those four.