I'd say David Arquette winning the title was the best first time win of all time.
Seriously though, Benoit and Eddie the same night should be listed in the best first time world title wins of all time. Hogan's was obviously the most important for wrestling.
Savage's title win is unprecedented as he beat four different guys to win the world title. He was the first guy not named Hogan to win the main event at Wrestlemania. To me, Savage winning the title for the first time and the pomp and circumstance afterward was a bigger moment than Hogan slamming and pinning Andre in front of a record crowd. Warrior's win was just as big as Savage's as Hogan had never been pinned but, as one poster replied, Warrior didn't stick around long enough for that title win to mean as much as it would have had he had a more prolific career. Flair's first in WWF was really cool but he'd already won many world titles before. Hitman's first win wasn't even on TV but his second at Wrestlemania 10 was one of the best ever. Michaels first was amazing after an hour long match but I don't feel it was as big a moment because the match itself wasn't that amazing. It was long, but that doesn't translate to amazing although it's amazing they were able to go an hour and keep the audience on the edge of their seat. Stone Cold's title win is so underrated here in the polls, it was one of the defining moments in the history of wrestling. It was the 'real' moment that WWF started beating WCW. The Mick Foley title win is the most overrated of all time. Mick Foley really had no business winning the world title. All the revisionist history about how everyone supposedly remembers this turning around WWF's fortunes and hurting WCW is full of it. WCW was already falling, although (i believe) the night Foley won the title was one of my favourite Nitros in WCW history with the Fingerpoke of Doom swerve. The Rock's I actually can't remember but Benoit and Eddie's title wins are two of the most memorable of all time.
Goldberg's first title win, like Warrior, ranks as one of the best but it doesn't rank as high as it would had Goldberg stuck around longer.
So i'm going to go with Savage's first title win, followed by Austin, Warrior, Michaels, Goldberg, Eddie & Benoit, Jericho and Hogan. If Hitman's second title win at WM X had been his first, then, in my opinion, that would have been the best one.