hard line

Mine is all stainless. Looks way better then copper. It is pricy though.

Mine is all stainless steel. I used compression fittings so I didn't have to flare the ends.

I have used copper with great success on numerous vehicles, it does slightly tarnish over time, but if you polish it and wax it it will stay nice for 6 months or so. I ran it on my daily driver that I drove in the rain snow and summer and have had no problems whatsoever. It is rated to 640 PSI for the 1/2 inch, and yes it is softer than stainless, but if mounted correctly will not be a problem.

Of course stainless looks considerably better, and can handle more pressure, but it is considerably harder to work with, damn near impossible to repari roadside whould anything ever happen and its 2 - 3 times the price of copper. Both ways will work just do what is going to work within your budget and skill level.