I've owned both of these sets in my living room (purchased
retail units, not review samples), had them calibrated and watched a lot
of Blu-Ray content on both and did some 3D gaming via PS3. There's no
question that the Sony HX903 is better than the Panasonic VT20 in 2D
mode, because it doesn't suffer from flicker, posterisation and obvious
motion processing errors (opening scene and the intro credits sequence
for Casino Royale is a good acid test for this); but the Panny gives less
crosstalk in 3D mode so it doesn't mean the Sony is better in every
aspect of PQ. If you watch a lot of 2D movies, the HX903 has the edge, easily.
If you do a lot of 3D gaming, then the VT20 would be the better choice.
Neither TV is bad, in fact they're both excellent especially when compared to the current
competing sets out there, therefore I think WHF's review scores for these particular models are right on the money.
Oh and by the way, my former TV before I made the leap to the 3D world was a professionally-calibrated Pioneer Kuro 5090, so I'm familiar with what a reference level 2D image ought to look like.
Take all reviews you find with a pinch of salt and always make your own judgment after auditioning the sets with your own eyes. I couldn't care less which accolades are heaped upon which set by which reviewers, I make my buying decision using my own eyes. A lot of reviews out there on the web are calling the VT20 "reference level", and that's exaggeration in my eyes, but hey, everyone's entitled to their own opinion.