The one that I own are mostly knitted cotton which is quite stretchy and snuggly when I put 'em on. It's all about slim fit which made the whole look quite neater, lessening the chance for it to went flip-floppy should I walk down the street in it. I know any man should have many polo shirts coz you can rock the casual/formal kinda way which is what people tend to go for it. But, well... what can I say. I'd rather wear a slim-fit shirt for casual events, than wearing a polo shirt that looks hideous. (Errks!)
So, if you have any trouble choosing polo shirts SHORTLIST mag gives you some selection from the high end labels to the highstreet find. Whatever it is - as long as it fits well on you and your wallet can stretch widely too - then get 'em! =)