EEG compatibility , what kind of EEG's can i connect to Max and How?

You can checkout the forum discussion here:
https://cycling74.com/forums/anyone-used-mindset-yet

there are several other threads, but this one covers most of the bases.

I have worked with both the mindset and the emotiv and I found that you really get what you pay for. In my experience the mindset was only sending out a data point every 1000ms or so, while the Emotiv was sending a constant stream. The mindset uses one sensor, whereas the Emotiv uses 14 (this is an exponential difference in quality really). And finally, the mindset sends very generic, high level data, whereas with the Emotiv you can get different modes of analysis. With the Emotiv it does matter which version you get, get the developer if you can. We were frustrated working with the consumer model. In summation, the mindset is really a toy in so many ways ( I found it analogous to the x-ray glasses I bought when I was a kid), whereas the Emotiv starts to move towards a research quality tool. Even the consumer model is miles above the mindset IMHO.