Flight attendants always pay attention to what shoes passengers are wearing. And it's not because they are obsessed with shoes or all have foot fetishes. It's actually to be prepared in case of an emergency. If someone is wearing high heels, they might not be able to run, so flight attendants like to take notice of particular things like this. Then they can remember to add emergency commands about removing shoes if necessary.
It's best to put on comfortable shoes that are easy to take on and off to make life easier when going through security and moving around the aircraft.