for the purpose of this comparison I will be using the current Black Canary, Dinah Laurel Lance, daughter of the original black canary Dinah Drake Lance.
Black Canary: Growing up Dinah Laurel Lance was surrounded by her mother’s friends from the disassembled JSA (Justice Society of America) & looked at them as aunts and uncles. She wanted to be like them and her mother although her mother discouraged it. She later met Oliver Queen with whom she was in the justice league with and would eventually become her husband.
Black Widow: Natasha Romanoff was orphaned as a child when she was trapped in a burning during an attack on Stalingrad. she was later noticed by soviet intelligence who trained and brainwashed her. Her & hawkeye tried to take down ironman & they fell in love, the KGB tries to gun her down because she begins to have less loyalty to Russia & hawkeye goes to the avengers for help. They both later join up with the avengers.l
Winner–Although Black Canary’s story is cool with the whole multigenerational thing however the edge goes to Black Widow’s spy background.
Powers & Abilities:
Black Canary: Canary Cry (which is a sonic cry with the ability to shatter objects & incapacitate her opponents. Has been able to convert her cry into brainwave form giving her the ability to read minds. She is an expert motorcycle rider as well as an expert martial artist (Suggested by oracle as possibly being better at combat than batman.)
Black Widow: Gifted intellect, world class athlete, gymnist, martial artist, marksman and weapons specialist. she has been injected with a variant of the super soldier serum used on captain america, she is also been enhanced with biotechnology that makes her body resistant to aging & she heals quickly. Her reaction time is virtually superhuman, great at psychological manipulation & covering her emotions.
Winner–It would have to be a tossup, the canary cry is awesome but so is the healing factor of black widow, they are both amazing martial artists.
Black Canary: Her mother is the original black canary, grew up around the JSA, had a relationship with green arrow, she was a member of the JLA as well as birds of prey.
Black Widow: trained by the KGB, member of the avengers as well as an agent for SHIELD, fell in love with hawk eye as well as daredevil.
Winner–Although Black Widow was romantically with two superhero & a member of some major agencies and teams this has to go to black canary and her association with not only JLA but also the JSA & birds of prey
black canary: blonde wig, black mask, blacks leather outfit/sometimes leather jacket, originally one piece & fishnets, often in heals.
black widow: black leather outfit, flat boots
Winner– Blackwidow, practical outfit, protected against the elements so she doesn’t freeze. Black canary’s outfit varies but usually isn’t very practical for the work she does.
Overall– It was close but black widow takes this.