[CMcAllister]

The best all around choice is the zinc coated steel line, typically called "bundyflex" in the old days. NAPA keeps it. Some of the others may or may not have it. Comes in a 25' roll at the auto parts. Roll it out and cut it to length. Better than grabbing a bunch of lengths and splices and cobbling it all together. Stiff enough that it holds it's shape when bent or straightened. Cheaper than stainless. Plenty adequate for what we do.

The green and the copper stuff is intended to be corrosion resistant for areas where they use salt on the roads. It is soft and easy to bend so DIY guys rolling around in their driveway replacing rusted brake lines can get it installed with minimum tools and effort.The problem with that is, it's soft. It's flimsy and won't hold it's shape well as you bend it or try to form it to look nice..

Stainless is nice, but overkill IMO, unless you are going to polish it up. And it is harder to work with.

Unless you are on a tight budget, everything gets done with 37* AN sleeve and nut hardware. Bulkheads to go through panels and tabs to hold it in place and provide a connection for hoses. Tees, bulkheads, adapters available for anything you may need to do. Just all around better than the auto parts SAE stuff. -3 Teflon hoses and steel or stainless ends for flex connections.

On a stock body restomod, S/SS type deal, I like to run everything inside the car as much as possible. Less clutter under the car and it's protected from damage. 3/16 cushioned clamps can be hard to find. I like a quality nylon clamp. Less bulky than a cushioned style steel clamp.

The Mastercool hydraulic flare tool with 37* tooling can't be beat. Other less expensive tools work fine. Get one that is for 37 degrees flares. The trick to nice flares is the prep before trying to flare it. Cut square and deburred inside and out with a little lube on the dies.