I use a Philips BDM4065UC, which is a 40" 4k monitor. I love it, and I have never noticed any type of lag. However, 4k for most systems is not a viable option because even the most powerful video cards of today struggle to hold 60 fps. My system holds 60 fps in AHII, and AHIII, but of course AHIII will probably change before it comes out of Alpha. That said. . .
A wide screen does make everything bigger and it is easier to shoot and hit what you aim at in AH, but there are caveats. If your system is not up to pushing the resolution you are using (like 4k) you may hit the lag issue, or 'stutter,' 'sticky frames,' 'slideshow' etc. depending on the setup. Fortunately, there are many methods to get smooth frame rates and that is the number one goal of gaming is to get smooth, consistent frames and not just a large screen.
If you do get a large screen, then I recommend a curved screen if you can find one that suits your other demands. A curved screen is not a primary need, but it will avoid the parallax view issue of screens that enter into your peripheral vision (wide screens can cause your brain to interpret the screen as being bulged in the center when it is not).
If you use a TrackIR type device then you should consider that you might have to affix the IR pickup below the top of the monitor, unless you are nearly seven foot tall.
All of this aside, from your description of your gunnery I do not think that a new monitor is going to fix things for you. I think you should spend some time in practice (training) in scaling your stick so that you might fly more smoothly. Usually, unintended rudder input (twisty sticks in particular), and touchy stick inputs will ruin your gunnery. In this game you absolutely must be able to put a reliable, steady weight-of-fire upon your target, or your target will just fly away.