I'm using an Acer 38" at the moment and find it really useful. I used to have two monitors next to each other but it caused neck issues to always look either left or right. I then made one of them my main front monitor and had the other one as a side for dialogs etc, which kind of worked. However, the Acer is extreme widescreen so it kind of gives you 1.5 of such a set up but you have your main viewing in the center. I now have a little bit less screen estate but I can use it so much better.
The only thing is that since it is so wide, but about the same height as my previous dual setup, I now feel there is space wasted below and that it would be great to have another couple of inches there, which would basically mean a 40 or 43" screen. The only options seems to be either the Dell 43", which is an IPS but seems to have serious burn-in issues, or the Philips 43", which is a curved VA that may be too glossy and apparently suffers from pixel retention. Still, the Philips may be an interesting option, a 4K monitor with about the same pixel density as a 27-30 monitor.