I have found that copper nickel brake line is FAR easier to work with, if you are buying bulk and bending your own. easy to bend form, no corrosion to speak of. You just have to have the skill to flare the ends.
I couldn’t agree with you more! I used CU-NI for all of the lines I have replaced so far and it bends beautifully but if you don’t have one of the pro flaring kits, that cost hundreds of dollars, you have to practice your flares. The biggest thing is to keep the flaring tool centered on the anvil. Check it just after contact and before you tighten it down. If its not centered, the flare will be lopsided and will not seal properly. Once I realized my mistake, my flares came out nearly perfect.
Here is the flaring tool I use. It’s an Imperial.