I’m not good enough to give recommendations, but meanwhile some questions might make it easier. What is your budget? Is open source important to you? What’s the biggest thing you want to print? Are there any special features you’re looking for? Do you want to tinker with it or rather have it “just work”?
It creates an effect where surrounding air is pulled with the stream due to the Bernoulli effect. It’s the same thing that pulls shower curtains in when you shower. If the fan is a bit inside the window, surrounding indoor air gets pulled into the stream, moving more air out in total.