Poor Harry. Throughout the Harry Potter franchise, the Boy Who Lived really just wanted a loving family – but of course, that just wasn’t meant to be. His parents were murdered by Voldemort, his Aunt and Uncle were abusive and cruel, and while he found some semblance of family with the Order of the Phoenix and the Weasleys, this was all too brief.
In fact, of all the potential father-figures that Harry had during his teen years, only two really stand out: Dumbledore and Sirius Black. His Headmaster and his Godfather were wildly different, though, with the younger Sirius being much more rash and keen to see James in Harry, and with Dumbledore being manipulative, but wise and mysterious. So who was the better mentor for young Harry, and why?
It could be argued that Dumbledore loved Harry, too, and he certainly was aware of him since infancy, but this is on an entirely different level to the kind of love that Sirius felt for his godson. Sirius loved Harry’s parents as his best friends, he loved Harry since before he was born, and he cared about him more deeply than Dumbledore could -especially given the Headmaster’s long term plans for the boy.
This isn’t Sirius’s fault, as he was framed for murder and left in Azkaban, then stuck on the run, and finally, stuck hiding at Grimmauld Place. However, the simple fact is that Harry had significantly more time with Dumbledore, and was able to connect to him and learn more from him as a result. He loved his godfather, but a few meetings and a single summer just aren’t enough to compare to years of a relationship.
As James’ best friend, Sirius didn’t just love Harry, he loved his family – and would be able to know just how James would have (likely) reacted, or how he would have wanted his son to be raised. In terms of a father-figure, Sirius was the person who knew Harry’s actual father best (even including Lupin, although he was also very close with James). When Harry was looking for someone to act as a father, Sirius is definitely more like James would have been than Dumbledore would be.