You are being way too kind with Stan. "Plenty of girs who are Stan-tier"?, the only one is an "uncorrupted" Holly with Ian paying her no attention and only because her low self-esteem might make her undersell herself and settle for Stan. Maybe also the landwhale, but she would probably think herself much better than him.The thing is what they are both looking for is a good looking person who will give them attention. There's plenty of girls who are Stan-tier in both looks and attitude but surprise, surprise, Stan would rather wank to super models and dream they'll accept his sword.
And while Louise is decent enough looking to maybe meet Stan's inflated standards of what girl he "deserves", Stan is obv. not meeting similar standards Louise is setting for her potential partner.