For me, it was looking at some real-world examples of what's been used where, and applying my personal PERCEPTION (which may not reflect reality)...
I asked myself what pistol I would believe would be reliable in a week-long heavy shooting course (1000-2000 rounds in that timeframe with few problems, low fatigue). I don't expect to run into that situation very often (just can't afford it!) but it seemed like a decent litmus test for reliability. That really shortened my list quite a bit, and I just couldn't find that much about Rugers being used to that extent...not saying it's not out there or that they can't stand up to it, but it's just my perception.