Actually, FLdigi is the best I've found, and none are perfect....nothing beats the human brain when decoding CW. The ARRL/QST new technical editor KE0OG recently did a YouTube review on computer/software CW decoders and does an excellent job explaining why our brains will always be the best, hands down.
I rely on FLdigi when I'm trying to copy QRQ speed demons, particularly during contest time. Some good CW practice software out there for learning code and increasing your speed. And of course, the tried-and-true method just start listening on the air.
After many many years operating digital, I'm moving back to CW - my first ham radio mode starting back in 1965 with a Knightkit T60 xmtr and Lafayette general coverage rcvr with bandwith wider than a barn door.
GL/73