I know it's academic at this point BUT Mantle was probably a better all-around player than Ruth. Much better fielder, switch hitter with 500 homers and played in an era where stats were down rather than Ruth, who played in the lively ball era. Mantle's stats, adjusted by Bill James to our modern standards, are awesome. Plus, he could run, at least before his legs gave out. Then there's that short right field fence at the original Yankee Stadium (the one Ruth built) that inflated numbers for lefties. Ruth was a helluva pitcher though. Can't sleep on that.
Sorry--I'm a huge Yankees fan and couldn't resist.
Z and JTR have a lot in common, and as I've said in another thread, I think Zodiac was definitely inspired by Jack the Ripper. Both wrote letters (I think the "From Hell" letter is authentic) to the press or local officials (in Jack's case). Z mailed swatches of his victim's shirt, whereas Jack sent a kidney to the head of the local vigilance committee. Neither were caught, the number of victims is debatable, both taunted the popo, and misspelled words (don't know if Jack's was on purpose or not).
That said, I too would probably give Jack the edge. His crimes were indeed much bloodier than Zodiac's. Both were, essentially domestic terrorists. And extremely lucky ones at that. While serial killers have been documented since Roman times (Procrustes), Jack was indeed a very modern serial killer who benefitted from the lack of criminal science during the 1800s. They couldn't even distinguish human blood from animal blood at that time. Z too was probably the first really modern killer of the 20th Century (unless you count somebody like Harvey Glatman), and he was about 20 years ahead of modern police work (DNA etc.).