I'm not a close follower of videography, but according to google your options have the following sensor sizes:
Sony NX70P: 1/2.88" sensor
Canon XA10: 1/3" CMOS Sensor
Sony VG20: APS-C sensor
In theory the VG20 should offer superior image quality with better dynamic range and low image noise. However reviews seem to suggest that the unit offers poor value for money in terms of features.
Actually modern day cameras with liveview offer very good alternatives to dedicated video cameras. In fact the 5D Mark II has secured quite a reputation amongst amateur videographers as an extremely good full-frame video camera that offers very good value for the features within.
It may be that the video camera and the DSLR are both slated for extinction in the medium to long term - just like film has now been on the endangered list for some years now.