I'm not sure of the true specifics you are asking about. That level of research would likely be done by a projector manufacturer like Epson would deals with it every day, but nothing is really published.
The reality remains that projectors aren't magic stand-alone devices, they receive content from a computer, and most often these days, it is from a laptop.
The MOST common laptop aspect ratio is 16:9. It matches all consumer televisions that are in existence and the vast majority of monitors on the face of the earth are now 16:9 aspect ratio as well.
If you check a place like Newegg.com or even Dell, you will find that the aspect ratio has pretty much been locked into 16:9.
There is also the 16:10 aspect ratio, which receives a fair bit of use in the projection industry for absolutely no reason at all. But, the use of a 16:10 projector doesn't mean that a 16:10 screen is used. Many, if not most, projectors allow you to choose the screen aspect ratio. So, if you have a 1920x1200 projector, and use a 16:9 screen, you set the projector to '16:9 screen' mode, and it turns of the top and bottom 60 pixels leaving the projector operating as a 1920x1080 projector.
A company that is hot in the interactive whiteboard market is Promethean:https://www.prometheanworld.com/products/interactive-whiteboard-systems/images/ActivBoard_10_Touch_SS_0617v1.5_US_EN.pdf?language_id=1
They have adopted 16:10, because it matches their bottom of the line projectors they purchase, and they aren't a very forward thinking company. They also have 4:3 stuff, but no modern consultant would recommend that as a solution.
I would stick with 16:9.
The resolution is a bigger issue as almost everyone in the business world demands 1920x1080 resolution, yet the schools all are buying 1280x800 projectors. Once again, 16:10 projectors, which should work fine in the 16:9 aspect ratio, matching the screen built into the laptop.
It's all really, REALLY stupid right now and very poorly thought out, engineered, and managed.
- Theater, whole house audio, and technology consultation during the build and installation process in the Washington, DC metropolitan area.