They're honestly all pretty damn good. Riot would surely try all of them and pick which one looks best based off the actual in-game model. 1. Is more like her classic look, 2. is probably more practical attire, and 3. is probably the type of look Riot would go for if they still wanted Caitlyn to have her skirt.
I feel as though Riot would need to do a 'Traditional Caitlyn' skin simply because they be making her hat marginally smaller and she wouldn't have a short skirt and bare legs. I agree that Riot should realign Caitlyn's appearance with her actual character, but at the same time what she should be and what people have grown to love over several seasons are two very different things.