I see both HDPE and LDPE tubing advertised. Is one better?
In terms of water? There is no difference. If you were piping and storing acidic or alkaline fluids, then there would only be one choice for each.
HDPE will likely last longer if left alone once put in place, and LDPE will get brittle sooner, but if you need to flex your tubes periodically LDPE may be your better choice because it is more flexible and will fatigue less if you are Moving your irrigation around.