ooh that's a tough decision you've got there.
First, I would take sony out of the options because they started to really get behind on the TV since all the technology started getting "Smart".
So now, it's Samsung or LG.
I used to like Samsung's electronics and I still do. They make one of the best electronics out in the market.
But I can't say the same with TV. I think LG really is stepping up the game now. When I first watched an LG TV, I told myself this is something different.
I instantly fell in love with how each colors pop out really good, enchancing the whole experience with the TV.
Since you mentioned the functionality of 3D, if you have LG TV in your living room, you will never have to visit the theater to watch a 3D movie.
You can convert any 2D video to 3D and it uses the same passive 3D technique as the theater and the 3D quality is hands down just awesome.
And I think you're like me, I used to be all about the graphics and not care about the smart TV functions and features but LG has a really cool interface.
It uses a remote where you just point at the screen (kinda similar to the Nintendo Wii) so it's much easier and faster to use than the old button remote.
From my experience with Samsung, I wasn't completely satisfied with their graphics.
It wasn't bad but I wouldn't say it was great either. It's really just a decent TV.
Besides, they have a really poor 3D functionality.
It requires you to wear an active 3D glasses which lets you see the 3D image by using the flickering technique.
They say you can't notice the flicker but it gave me a headache after a few minutes of using them.
Not to mention that those glasses cost like 70 bucks per pair, it's run by batteries meaning it can ruin your movie half way through.
Having considered these aspects, I would go with the LG TV.
Hope this helps