I'm basically repeating what has been said before, but any pre-war all electronic TV is very rare, historically significant, and highly sought after, especially if it is in good condition and complete. It's just a matter of which are the rarest to pin-point which is the most valuable. The mechanical "scanning disk" sets are very valuable too, but, because they are basically just a static display, they appeal to a very select group.
My own personal opinion for the most valuable TV would be the RCA experimental "RR" series of "mirror-in-the-lid" televisions. Any collector, including myself, would very much like to have one in their collection!!
