Who was most likely Jack the ripper? Is there any consensus opinion among historians?

There is no current historical consensus on who was Jack the Ripper; nor is there really a most likely candidate at this point. There are several individuals who might be described as less-unlikely candidates when viewed through the overlapping lenses of modern criminal psychology and the historical record of suspects considered by contemporary law enforcement. (This category includes Aaron Kosminski and Montague John Druitt, both of whom were on contemporary investigators' radar.) There are other candidates who might be described as more unlikely without much disagreement in the broader community -- individuals not under Scotland Yard suspicion at the time of the crimes but identified in hindsight by amateur sleuths chiefly due to their status as high-profile public figures with somewhat shady private lives. (Charles Dodgson, Prince Albert Victor, Walter Sickert, and James Maybrick all fall under this category for me.) There are still other candidates who exist somewhere between these two extremes, and still other hypothesized profiles of totally unidentified perpetrators. These various classes of candidates might appeal to true crime wonks like me, but all evidence remains circumstantial and fragmentary; a lack of rigorous supporting evidence and a lot of conjecture doesn't add up to good historical process or compelling criminal psychology. There have also been a number of outright hoaxes and forgeries which muddy the waters, from the hundreds of fraudulent letters sent by disgruntled or simply perverse Londoners in the weeks and months surrounding the attacks to a supposed diary implicating Maybrick that turned up in the early 1990s. Hoaxers, both modern and Victorian, hold in common a desire to insert themselves into a sensational case and to press a single desired conclusion by any means necessary; they both do damage to the historical record. Anyone who touts any kind of unanimous conclusion among historians and aficionados of the Ripper murders, even a purported agreement regarding the number of murders committed by the Ripper or whether a single Ripper existed at all, is trying to sell you something. (Probably a book.)

The window of time has passed for any kind of forensic examination that would remotely satisfy a modern courtroom, due to the developing state of 19th century English policing and a limited contemporary understanding of the motives of serial murder; all eyewitnesses are long-dead, as is the perpetrator of the crime, and so are the canonical victims' immediate loved ones. What use is there in studying the Ripper murders if we can no longer identify the killer? The Ripper case isn't a historical stand-alone that can be solved by a decontextualized handwritten confession or a smear of DNA. You can study the details of the case as a collection of stand-alone datapoints, or do your best to reduce it to a sterile forensic study, but to approach the case from a historical perspective is to fling a door wide open onto a much more complex curriculum of historical study -- not just a handful of days in 1888, but a wider social and chronological context. It's worth talking about the Ripper murders in terms of what we can learn and have learned about the material world and especially the print culture of late 19th century London -- police reports, newspapers, letters, memoirs, witness statements, even graffiti; for what we can learn about public attitudes toward crime, class, gender, Whitechapel's Jewish community, the press, policing, and the lives of women who did sex work. What can we learn about homelessness, public housing, labor rights, contagious disease, forensics, and how contemporary Victorians understood these things, or the day-to-day experiences of working-class men and women, immigrants, religious minorities, laborers in all jobs, newspaper readers, crank letter writers? All these things existed in late 19th century London outside the context of the murders of these five (or more) women, but study of the Ripper case affords an opportunity to draw sometimes disparate topics together for easier access and contrast. What can we learn about the historiography of violent crime, and the long shadow of the Ripper over later criminal cases -- is the archetypal killer understood to be an immigrant laborer in a dirty apron, or a gentleman intellectual with connections in the corridors of power? How have these conceptualizations of the Ripper crimes impacted real-life policing and legal precedent? How have the methods employed by law enforcement and journalists alike during the Ripper investigations impacted the lives of individual men and women, even decades later? There's a lot packed into the Ripper case and its adjacent topics that has little if anything to do with the specific identity of the crimes' perpetrator, and that lend the case an enduring interest even in the face of changing attitudes regarding victims and perpetrators of crime.

I would urge you to be skeptical of the ongoing cycle of announcements that the Ripper case is closed at last, due to DNA evidence or anything else. The two most prominent claims to solving the Ripper identity question using DNA (the theory proposed by Patricia Cornwell implicating Sickert and the theory proposed by Russell Edwards implicating Kosminski) are both inconclusive, and the 130-plus interval between the deposition of any supposed DNA evidence and its recovery in 2019 renders the provenance of both Cornwell and Edwards samples pretty doubtful.