1TB is a confirmed buy for me now, question now is, which one ..
I have 840 EVO locked at $350, but maybe I can get 850 EVO in 10 days for $100 more .. But I don't know if it will be worth the slight difference in performance .. Plus, newly released stuff sometimes have terrible issues in them .. The 840 EVO itself is damn expensive for me (I can buy an Xbox One in the same amount!), so I really don't want to go over and above $350 ..
Decisions, decisions .. :/
You're overthinking this decision far too much. As you have been told multiple times in the thread, choices between SSDs you won't personally notice. If you had the 850 EVO for 1 week, then someone swapped in an 840 EVO, you wouldn't notice. This is more for people who are on the cutting edge and need to extract every ounce of performance they can get.
You simply need a good price per GB SSD.
You're simply doing: excel, word, programming work, web browsing
As another user said, you could buy a 240GB SSD for like $60 on sale (slickdeals has them constantly) and get an external pocket sized external drive that's 1TB-2TB and come out cheaper than an 840 EVO 1TB. For convenience sake, you should just get the 840 EVO 1TB (or whatever SSD you can find that's decent that has 1TB).