We went with a 1080p projector (which does, in fact, do 3D when desired), and, for a screen that large, it's something to consider, but if your room has a lot of ambient light it's not as good as a TV.
4K just got standardized HDMI signalling, so if you do go that route, then it'll be ready for 4K content as you upgrade other components in your system. Given you're buying such a large TV, I expect you don't replace it frequently, and in 5 years there's likely to be a lot of 4k content. So I wouldn't dismiss 4K just because there's little available now, but it is an additional cost, and even 5 years from now 80% of the content you view is still likely to be 1080p. Note that if your audio/video switcher/amp doesn't support 4k or 4k passthrough you'll have an added expense the first time you buy another 4k component.
I'd probably focus more on the framerate (120Hz if you don't care about 3D, 240Hz if 3D), and the LED backlighting. Newer TVs obtain better blacks by having a matrix of individually selectable LEDs behind the LCD, and particularly dark areas of the screen dim the LEDs. This means that even if the LCD has a poor contrast ratio, deeper blacks can still be obtained. I don't know how common this is now (Happy with my projector...) so you'll have to do a little research to find out who does this and what their particular trademark is for it so you can compare TVs.
If you get a 4K TV, it's worth getting the built-in netflix or roku. They will actually stream 4K content to you, but current set-top roku boxes and similar don't support that yet.
If you're not getting 4K, you should focus more on the TV quality and ignore any built in stuff. Use an external roku, the built in boxes are never upgraded and usually just complicate the remote, becoming useless after a few years when everything else is upgraded.
Note that there are no 4k blurays or 4k bluray players. There are "4k optimized" bluerays and "4k ready" blueray players. The idea is that the same 1080p resolution is encoded on the disc, but it's encoded in a way that makes it easier/better to upscale to 4k than without this encoding. It's better than 1080p on a 4k TV, but it's not 4k. I know they've got stuff in the works, but they're struggling with a few issues (do you really want to switch the disc in the middle of a 90 minute movie?) and I think the streaming industry (directv, netflix, comcast, etc) are going to finally get what Apple's been trying to do for years - the death of physical media.
But everyone seems to agree -
it's not really worthwhile investing in 4k devices right now.
Spend the extra money on a TV with better blacks, better colors, and a good refresh rate so you can view all your content correctly. Then spend some time calibrating it.[DOUBLEPOST=1426697563,1426697255][/DOUBLEPOST]If you can get an IPS panel, it's worth it. Better colors, better viewing angle for everyone in the room.
Also, if you do get 4k, this is obviously the one to buy:
Amazon product
Better hurry, though, Amazon only has one left in stock! Free enhanced delivery too, which will come in handy as they muscle the 250 lb 98" behemoth up your stairs.[DOUBLEPOST=1426697696][/DOUBLEPOST]Also, the first real 4k blu rays won't be available until later this year - if then.[DOUBLEPOST=1426697740][/DOUBLEPOST]Broadcast 4k is a loooong way away. Years at the earliest. I'm guessing the 2020 olympic games might feature 4k broadcast TV if everyone gets their act together now.[DOUBLEPOST=1426697782][/DOUBLEPOST]I wish the "Double Post Merged" notice incremented correctly.