I've been through a handful of straight and right angle MIDI cables...and the winner is the One Control Hammer Angle MIDI cable. They won't pass power, so if you have MIDI powered devices it's a no-go but if you're looking for the best to be compact, it's the choice. None of the right-angle cables worked for me at all. They almost all cover other ports/connectors on every pedal.
Have you tried the latest Rockboard flat or flax MIDI cables? Those look pretty small...
I have the OneControl cables as well, since they were the lowest profile I could find where you can also change the orientation