Emotiv EPOC+ Research Edition can be used on Windows, Linux and Mac. 

It has 14 electrodes and is used in several publized studies. 
You can access Raw Data via their Software "Testbench" and outpur it as CSV or use third party Software like OpenVibe, BCI2000 and EEGLab.

But the little drawbacks: 

 - It is a wireless device, so you really should put the usb dongle for wireless signal transmission with a long usb cable directly on the device

 - The reference electrode processing is done within the device