I am using the Epson 3100 retractable screen. The setup takes approximately 4 minutes. Once set, I found the screen to be almost completely horizontal. If it's not horizontal, you can actually adjust it a bit by moving it to the top hook.

$59, the picture quality is very good. The film has good contrast and clarity. Dark scenes look dark, but still retain details. This may not be suitable for 4k projectors because the weaving on the screen may not be fine enough and will interfere with 4k resolution. In 1080p though it is good enough.