Buying a 5 or wait for the 5s / 6

I bought the iPhone 4s last year and it still is an amazing phone, everything still works fine but after the iPhone 5 came out, it feels like the 4s isn't good enough any more. Buying the iPhone 5 is no problem (financial) but should i wait until apple releases their new iPhone and buy that one, or should I buy a 5 right now? And why should I pick the one of your choice?