I've been pretty happy with RedBearLab's BLE hardware. I've been using their BLE Mini implementation for many projects recently, which also has it's own iBeacon firmware available. They also have purpose-built iBeacon hardware available: http://redbearlab.com/ibeacon
Their support is better than most and it seems to be reasonably popular within the Arduino community so there is a reasonable amount of experience with it available out there on the forums.
Personally, I've enjoyed working with their BLE Mini hardware the most as their open-source "Biscuit" firmware has been fairly straight-forward to modify and compile.