I have an LG 3D TV at home and I strongly believe I have made the right decision. The design is simply awesome. LG has the slimmest and slickest design. The dual-core processor makes browsing and streaming videos awesome. If you are looking for a greatly deisgned television, out of this world quality, and smooth operating, I recommend you to get the LG Television.
You have to know that for the 3d aspect, Samsung and Sony are similar (active 3d) but LG is different (passive 3d). Active 3d tvs produce flicker which is normal and they come with battery operated glasses. On the other hand, passive 3d tvs are flicker free and come with lightweight glasses. Some people say active 3ds are better in picture quality but for me they're just the same. I have my own lg smart 3d tv and my advice to you would be to choose a tv not just because of 3d alone. Consider other features. I got my tv because I liked its overall quality and features. It would also be best to go to the stores and try them personally to find what suits you best.
On the basis of multiple surveys LGs LM series models are tremendously way better to consider than any other available options. Both other brands you’ve mentioned are using active 3D technology which means heavy 3d glasses and viewers might face flicker & crosstalk at times, whereas, in LG passive 3D TV we will get comfortable passive 3d glasses with no attached batteries. PQ and sound quality is just amazing!
Actually I think Sony makes excellent active 3D sets, if the person wants active. The hX929/850 are great tvs. But there is a better 3D TV imo and that is lg's passive sets. The 3D is just too fitting for the masses and I find the advantage passive glasses have over active invaluable.
Active and passive 3d tvs have their own pros and cons. Some say that picture quality of passive 3d is inferior than active 3d but this is not the case with my experience. Others claim that flickering in active 3d is too bad. I myself don't know if it happens all the time. That time, when I tried an active 3d tv in the store I experienced flickering because the glasses has low battery. That's what I don't really like about active 3d glasses you have to make sure that battery is always full.