In terms of pure screen quality, the Nexus 10 hands down.
However, the Galaxy Note 10.1 has some advantages in terms of connectivity.
The Galaxy Tab 2 would be a distant third...not especially close.
IMHO, the hands-down best 10.1" Android tablet though is still the ASUS TF700T, with the best low-cost 10.1" going to the ASUS TF300T.
The TF700T has a great feature set that works very well all-around. It has a truly brilliant screen, great color, and is only a small step behind the Nexus 10 in resolution.
The TF300T shares most of the TF700T features, with the exception of a plastic back (versus metal on the TF700T) and a very decent, but less outstanding IPS screen.
P.S. Samsung uses the touchwiz overlay, which while not the worst layer over the Android OS, never the less is an uneeded addition and ensures that any Android OS updates to the Samsung tablets will come slower than for the ASUS tablets...something to consider. -- Deeds, not words