For me, the 2 most impressive 3D presentations I've seen thus far are
Madagascar 3: Europe's Most Wanted 3D
Rise Of The Guardians 3D
The reason for this is because thus far, those 2 movies have displayed the best attempts at 'erasing the screen plane'. In most 3D movies, the 3D is mainly used for depth. In some movies, popout is added for the gimmicky 'reach out and touch' fun, but in 'erasing the screen plane' the directors attempt to use and meld the depth and popout by having objects and characters moving in and out of the screen plane a lot more.
The effect, as I've described it elsewhere, can be likened to a window. With depth only, it's like watching kids playing with a frisbee outside your window. You see depth, but you are apart from their environment, separated by the window (screen).
With mostly depth, and occasional popout, it's like watching the kids through the window, but once in a while, something crosses from their environment into yours, eg. the frisbee comes through the window.
With 'erasing the screen plane', by continually having objects and characters extending into and out of the screen plane as well as moving in and out of the screen plane, after a while I can forget where I am and actually feel like I'm a part of THEIR environment, as opposed to being separated by the screen plane. The 2 movies above have thus far done the best job at it, and I hope to see many more directors using 3D this way.
As for live action, my votes would be
Flying Swords Of Dragon Gate 3D
Resident Evil:Afterlife 3D
Resident Evil:Retribution 3D
A partial list of just some of the other 3D movies I own (yes, I'm a big 3D fan):
Alice In Wonderland
Life Of Pi
Guardians of Ga'hoole
Toy Story series
Star Trek:Into Darkness
Puss In Boots
The Adventures Of Tintin
Jack The Giant Slayer
Transformers:Dark Of The Moon
Cloudy With A Chance Of Meatballs