All the brands of 3D TV are different, all have their pros & cons apart from bells & whistles.

PANASONIC - PROS - plasma so it should be cheaper , Deepest black level as it's basically a Pioneer KURO [best flat screens ever made]
CONS - Picture Flicker , Plasmas run hotter than LCD/LED, possible screen burn-in if playing games a lot.

SAMSUNG [7000 & 6000 series] - PROS - Cheaper than Sony , choice of Plasma or LCD/LED in their range.[wait for the 8000 series LCD/LED 3D sets]
CONS- Use edge lighting instead of back lighting, some picture ghosting,uses polarizing glasses so more light loss, glasses feel flimsy & cheap, same cons as Panasonic for Plasma versions

SONY - PROS - HX series [best picture in Sony range] can be bought as 2D TV then add glasses & receiver later for 3D, uses LCD shutter glasses so light loss minimal.
CONS- Expensive , limited sizes, 2D to 3D processing seems like an afterthought.

There's a lot of other differences, but those are the most basic.

You would want to make sure that any 3D TV you might consider buying was able to have it's 3D processing software up-datable,otherwise your set will be out of date before you get it out of the box.
The SAMSUNG 8000 series has had a BIG software update and it's only been out 2 months and is reported to of made a huge difference.