Well, we should be able to confuse you even more.
Oled are just coming out after trying to solve problems with blue (I believe) lasting any time at all. And they may have serious burn in issues. But the best picture.
No one can tell you how long a tv will last, but LED bulbs are suposed to last a long time.
Sony has a long reputaion for conversion and a very good standard and high deffinition picture.
4K is going to be the future (until 8K) but the HDMI 2 stanard isn't being incorporated into the sets at this time (but some are claiming upgradability).
There won't be much native 4K content for a few years.
The larger sharps have a very nice picture and imersion factor, but can be a littled grainy up close.
Samsung probably get the nod for a slightly better picture quality from a good source.
If you are going to be setting 15' or more, go for the 80 or 90". At 10 to 15', a 60 to 90" will work.
Vizio may have a higher failure rate, but most TV's have a sub 3% problem rate.
The sharp 857's have a super bright panel that holds up well to very bright rooms with sky-lights.
I have an 80" sharp 857 and a 60" samsung 7100 and after tweeking the settings they both have what I consider a spectacular picture. But both suffer a little with the standard deffinition channels. But I don't watch them anyways.
So, take your time and figure it out and you won't get byers remorse. Hope this helps.