I agree about the buried pipe. Use as big of an ID as you can, less friction loss over the length of run so the water will move faster. Above ground pipes/hoses are a PITA. Plus if it's not metal the sun will chew it up in no time and you will be buying more. If it's below ground just make sure you know where it is in case you want to dig in the future.

Being below ground you won't have to worry about driving over it, if it's plastic, you won't have to worry about critters chewing on it, or hitting it with the brush hog.