Here's another config I never see mentioned, but I love it. One giant 42" 4K TV. They are relatively inexpensive now (~$200) and it's roughly the same as having 4x 21" monitors conjoined in a square. It's very important to tone down the brightness and back-light considerably, since TVs are designed for sitting about 10 feet away, but they work great as monitors if you buy a good brand. Make sure your graphics card can support ultra high resolutions, and use a modern HDMI cable capable of 4K.

edit: Ensure 60Hz or higher refresh rate. This should be true if the TV is a good brand.

you need 60Hz and 4:4:4 chroma subsampling, otherwise text can look really bad. I don't know any models in the 200 range that support this.

30Hz refresh rate is brutal for some apps/people

4k tv's have been 60-hz for a few years now. You just have to make sure your video card can handle it.

Most 4k tvs, or at least the 250 dollar TCL model I have, support 4k at 60hz over the newer hdmi spec. It works fairly well as a large monitor, even when sitting up close.

Personally I don't think I'll ever get a <=60Hz monitor after using one with 144Hz. (Caveat- there aren't many 4K 144Hz models the last time I checked, and they're quite expensive. I'd rather make due at 1440p, any day!)

Does 144hz really make any difference in office applications? Gaming, obviously but I cant imagine it affects productivity at all....