Which eye antibiotic drop is better? i know each one has it's own class, but generally which is stronger polymyxin & trimethoprim or cipro (ciprofloxacin)?

All depends which: bug or bacteria you are trying to kill. That is the more important question. Otherwise you are building resistance to SUPER BUGS, and when you need to use a 'strong' antibiotic, it just won't work anymore. In that case, it becomes a weak antibiotic. Ask your doctor what you are treating to find out the bacteria in question. Then, answer it that way! Hope this helps!