If the run from the house to the street is short (under 60 feet) I’d use Type L soft copper. It is less likely to break and it has no fittings in the ground except at each end of the pipe. I’d also put foam insulation around the copper run. For longer runs my next choice would be schedule 40 PVC pipe. Not a bad choice at all.
I would not use flexible plastic – that is black poly pipe. It comes in a roll. It is too soft. Hard surfaces (rocks) rub holes in it and where ever there is a transition to another type of pipe or an elbow it will leak there – because of the hard adapter, radiator clamps, and the soft pipe. These connectors will break over time. I repair them weekly. Schedule 40 PVC or copper is the best way to go with water mains.