Samsung 51.
By the way, google around for screen crack issues on Samsung plasmas before deciding.
I agree. You get less visible screen-door effect and a less reflective panel with this option (plus a larger panel and a slimmer enclosure).
Of course, it's really up to the buyer to decide (some may gravitate towards the 50x30, as its predecessors have been proven "safe" buys).
@Tavus
Since your budget extends to 50k, have you considered getting a 3D model instead?