I use the kind that has three slots to bend the tube in, and looks like a mandrel bender, pulls the tube along as you go.
EDIT: Found a link..they are like 5.99 I think, autozone, napa, etc...
http://www.autozone.com/autozone/acc...er=391367_0_0_
But for a majority of my work now I just use the green aluminium line. You can bend it by hand, and flares real nice, and seals good too.