If you see a thread on the main forum, the latest tip is to have very few spaceports. Build star bases of a suitable size instead, with just docking, recreation, and medical (and maybe some weapons and stuff).
The main advantage of spaceport is the recreation and medical facilities. They boost population happiness. It helps population growth, and any bonus in happiness means you can tax a bit harder.
Docking bays are nice, but in shadows not so important anymore. A colony got 20(?) bays in shadows, while it was only 3 before that. But planet bays are slower (in throughput) than bays in space. Also, a colony without a spaceport should not see massive traffic, since the main hubs (with spaceport) will gather the most resources apart from what is needed of luxuries.
If I start a new game, I think I would make my default star bases somewhat like small spaceports without construction and research stuff. Maybe much smaller once the area is somewhat quiet.