Wacom touchscreen or pen input? I don't know of any eReaders that have pen input.

Also, are these devices properly GPL compliant?

They do have Wacom pen inputs, plus a normal capacitive touchscreen, and are also compatible with third party pens.

I haven't inquired about GPL compliance.

What are some models you recommend?

I quite like my Likebook, but I have the Mars model which doesn't have a pen input.