My 2 c:
The Robo 3D has an acrylic print bed, which is most probably not heated... It seems strange to me that they advertise it as ABS capable, since usually this would cause warping. But the website is pretty scarce on details.
The JapicaBot has the very interesting option of dual head, seems well done, not too much technological difference with respect to the SD3 but in general a more accurate design (eg bearings instead of bushings). The drawback is that it would be more complicated to add an enclosure
The SD3 is in the same class as the JapicaBot IMHO, maybe with a bit more sturdy frame.
It is hard to comment without knowing the other two printers. In general the SD needs quite some calibration and tweaking, but afterwards the results are very pleasing. I would expect the JapicaBot to be similar since it is derived from RepRap (I have a colleague who owns a self-assembled RepRap and it is much more complicated to get running than the SD).
Bottom line: I would go for SD3 or JapicaBot