I switch bags daily. I try to match the bag to the clothes I'm wearing but I always consider what I need to carry each day and where I'm going to (if I have to attend class I usually opt for larger bags that can fit all my stuff, if I'm running errands I carry smaller shoulder bags etc.). I also take the weather into consideration and prefer larger bags on rainy days because they can fit my umbrella. On a night out I carry either smaller shoulder bags or clutches that can fit my wallet, keys and cellphone.