I agree with the previous poster on the 6 am. Not sure where you are originating from, but say it was RDU. If Friday schedules are like today, your inbound aircraft is coming in from LGA. So, the 1:30 flight leaves you with at least a double exposure to LGA weather/ATC. The aircraft for the 6 am flight will have likely arrived the evening before (and if it doesn't, you don't have to wake up early).