Velcro is cheap and comes in as many colors as zipties, with the added benefit of being able to redo your cabling as you need.
Zipties are ok for a semi-permanent to permanent setup, but any that are exposed to sunlight or heat will have a tendency to become brittle.
For a professional look (if you have the time and patience) lineman knots with wax thread is strong and secure. (For outside your PC, inside the thread will yellow and brown from the heat and then it looks and feels nasty.)
You can get adhesive tie-downs to secure to walls and tables, and can be found using non-marking adhesive for less mess when removing them.
Whichever method, do not make the ties too tight, you can pinch or internally break cables, which can be a real pain to fix after taking all that time to bundle everything just to have to undo it all. Just snug is fine, they aren't going to run away if you leave a bit of slack.