I use a single flare 45 degree angle block flaring tool for oil. It has lasted me 13 years so far. It is a Ridgid ratcheting type.
I bought a 45 degree angle Rothenbeger for double flares in case I run into replacing a suction line filters on AC where I might get a burnout. I tested it and took a little bit to get good at making the flare but haven't used it in the field yet.