I'm looking for help choosing a 20". How come TH readers don't reply to threads of buyers looking for a 20" or 22" monitor? :-/
Out of your choices, I would choose the Acer for the reason you can find reviews on it. Look at the newegg site. The Acers with the X200 series have decent reviews so there is a good chance you'll be satisfied with the monitor. Also, it appears it has better specs than the Sceptre.
I'd go with a computer brand name, also. I have no idea about Sceptre products.