Assuming that there are no restrictions like the ratio of a screen; what is an eye pleasing ratio for presentation slides and handouts (containing information about the presentation)? Is it something to consider or negligible? Can it be generalized?
I'd say both 16:9 and 4:3 ratios are equally pleasing, but they do depend on the screen you will be using and the information you will be showing. 4:3 is the resolution of most laptops and computers, and 16:9 is the standard aspect ratio of Blu-ray discs and HDTV signals. You can watch 4:3 content on a 16:9 display, however, you will see black bars on the top and bottom or along the sides of your image.
One thing though, once you decide for one of them, converting it to a different ratio could be tricky. So it's better if you choose one and stick with it.