I use the AZ "OEM" brand tool. I guess its one step up from the cheapest. Has worked fine on many mild steel flares for brakes and fuel. No leaks. I haven't and wouldn't try it on SS... and would not run SS for that matter as it is a PITA to flare and seal. Other pointers are make sure your cutting tool is sharp and remove the "rim" inside the tube after cutting and before flaring.

As far as benders go, I have two... a pretty good one and a simple one. That said, usually bending by hand seems to work best for me. If I want it "pretty" professional line sets by Inline Tube are the ticket. Otherwise hand bent is OK and functional.