I use a bench vise and socket with great success. I always works and usually leaves the cotter in good enough condition to reuse. Search this forum or google it to see the details.
Cottered cranks are not substandard equipment. They work great but do take a bit more effort to disassemble. I am looking for a cottered steel crankset for my commuting bike to replace the square taper set. I have broken too many alloy cranks to trust aluminum any more.