I'm looking at this straight from a bodybuilder standpoint:
I see that you want to get stronger over time. Doing a routine over a period of time will allow you to get stronger with correct progression. Now what should you do first, Leg Press or Squats?
First off, not too sure of your training level or experience but I see nothing wrong with doing leg press before squats. Of course if you do squats, you won't be able to go as heavy as you would want to but you are still getting the work done. It won't hurt to give it a try and see how your body feels. Or another way, alternated between the two exercises of which goes first.
Im all for experimentation and some are not. It's a personal preference.