I have never seen the Panasonic 50EM5, but I did buy a 50L2200U as a gift for a family member and helped adjust/pseudo-calibrate it a few months ago. I found it to be a great bang-for-the-buck TV. Excellent overall uniformity from being backlit, although the one i bought did have one minor bright spot in the lower-left corner, but it was so minor that it didn't bother during dark scenes or letterboxed content. The L2200U exhibited excellent overall contrast good black levels for such a budget TV. Motion was present but overall pretty minor. I did not try it with any video games, though. If the Panasonic really is edge-lit, then I'd say that would definitely tip the scales in the Toshiba's favor.
ht Panasonic 60" ZT60, Monitor Audio: Silver RX6, RX Centre, RX1; Martinlogan Dynamo 700, Marantz SR5006, PS3, Oppo BDP-103D, Panamax M-5100PM
2ch Sony 32" W650A, Sonus faber Toy Monitor, REL T3, Marantz PM8004, Sony BDP-S1000ES, JVC T-X3 tuner, Apple TV, Peachtree Audio DAC•iT, Panamax MR4300
pc Monitor Audio Radius 90HD, Audioengine D1, FiiO A1
+ Sony 65" XBRX850B, Sony BDP-S5100