Which monitor would be best?

[dslatsh]

Hey everyone, Happy thanksgiving, but um I'm looking into wanting a bigger monitor, I got a new desk and the way the desk sits my little 27" isn't as big as I'd like it I guess so i'm debating of getting a wider bigger screen or doubling up my 27" which i currently have a Asus which is below, I was looking into 4k however the prices are craaazzzy. I was looking at the "2k" monitors and have heard some pretty good reviews on these. Any other ideas would be beneficial, I was hoping to not spend more then $400 on a monitor right now,

http://www.newegg.com/Product/Product.aspx?Item=N82E16824236313

Right now there's a sale on this acer,
http://www.newegg.com/Product/Product.aspx?Item=N82E16824009769&cm_sp=Homepage_BS-_-P9_24-009-769-_-11242016

And i was also looking at this LG which has really good ratings,
http://www.newegg.com/Product/Product.aspx?Item=0JC-000D-003Z3&utm_medium=Email&utm_source=IGNEFL112216&cm_mmc=EMC-IGNEFL112216-_-EMC-112216-Index-_-LCDLEDMonitors-_-0JC-000D-003Z3-S0B

 

[hdmark]

if you have an AMD card, the acer would be good due to its freesync. id also prefer the Acer for its 2560x1440p over the lg which is a wider monitor. but thats my preference

 

[dslatsh]

I have Nvidia, and I noticed that too for the acer, but question is do I combine and do a dual monitor using my asus 27 and the acer 27?