Short answer: I followed both men fairly closely during their careers, but I don’t think this question can be answered, because the sports differ too much.
Long answer:
Tyson won 100% of his bouts over a period of several years, while Tiger won “only” 50% or less of his tournaments. But Tyson only had to beat one guy at a time, while Tiger had to beat up to 150 guys in each tournament, and he played in all the toughest tournaments.
And he didn’t just win, he won by 8, 10, 12, 15 shots. At his peak, he not only had the best overall game; he was the best driver, the best iron player, the best short game player, and the best putter. I doubt we’ll ever see that again.
On the other hand, Tyson was devastating for many years. He didn’t just win, he destroyed his opponents, usually in a very few rounds.
Sports fans are notoriously inconsistent when it comes to determining the GOAT. They will tell you that majors are all that matter when it comes to comparing Jack with Tiger, but I have yet to meet a Jack fan who rates Walter Hagen, with 11 majors, ahead of Ben Hogan, with 9 majors. Wait, you say Hogan would have won more if he hadn’t been in that accident? Well, I say Hagen would have won more if he hadn’t hit his prime before the PGA or Masters were even founded, and the British Open required a month of round-trip travel time, and even that was cancelled for several years for WWI. You say Jack had tougher competition? The PGA championships he played in the 60’s had only 50 or so touring pros in the field, and 100+ club pros. The British Opens he played in the 60’s all had less than a dozen American touring pros in the field, and sometimes less than half a dozen. Palmer and Player also padded their record playing “majors” that had weaker fields than almost any regular PGA event today. Player’s first major win, the 1959 British Open, had exactly zero US touring pros in the field.
It’s amazing to me how many golf fans contemptuously dismiss the efforts of the PGA Tour to promote the Players Championship as a “fifth major,” in spite of its extremely strong field, and yet uncritically accept the majors of the 60’s that built Palmer’s, Player’s, and Jack’s reputations, when they typically had fields consisting of only half the world’s best at a time — either almost all Americans and only three or four international players, or the opposite.
Similarly, it’s amazing to me how many boxing fans rank Tyson outside the top ten of all time because he didn’t fight Max Schmeling or Billy Conn. FFS, he fought several world champs in a row to unify the heavyweight title for the first time in years. These were guys who were like 6’-5" and 220 pounds of solid muscle. Joe Louis and Jack Dempsey were great in their time, but Louis weighed 190 and Dempsey weighed less than 180. There’s a reason they had to make a new cruiser-weight class, because unlike the old days, when a guy over 220 like Willard was likely to be a big fat oaf, they are solid muscle today. A guy the size of Dempsey is just too small to fight an elite heavyweight today. Tyson outweighed him by 40 pounds, even though he was shorter. And make no mistake, Tyson was fast as lightning.
My definition for GOAT is not the won-loss record, it’s who would win if the contenders competed against each other. I think Tyson in his prime would beat any previous champion (I stopped following boxing about 20 years ago, so I don’t know about more recent fighters. I can’t even tell you who the champ is now).
And I think that Tiger in his prime would beat any other golfer (I do still follow golf).
So IMO they are both the most dominant in their respective sports, but the sports are too different to compare them directly.