Even though Bret passed that torch at wm 12 he was scheduled to beat HBK at wrestlemania the next year until Shawn faked that injury and the match had to be rearranged. I'm sure Vince wanted HBK to be the main guy in that period but business indicated that he had to look elsewhere and I assume they went with Taker/Sid because they were both giants.Shawn Michaels became the face of WWE and the main man in the company at WrestleMania 12 and he was the one who passed that torch on to Stone Cold Steve Austin two years later at WrestleMania 14 so seeing how Shawn Michaels was the main focus of WWE in that time i would have to go with him. When Shawn Michaels beat Bret Hart at WrestleMania it is widely accepted that Shawn Michaels had become the main man and was the one who Vince McMahon believed would carry WWE into the millenium.
Obviously Stone Cold Steve Austin was not expected to go on and become the HUGE superstar that he did but in reality he did not blow up until THAT segment with Mike Tyson which saw Stone Cold Steve Austin go from top face to mega star. In 1997 i would say that the feud with Bret Hart and then Owen Hart saw Stone Cold Steve Austin become a big star in WWE but he was never the face of the company until he won the WWE title so in my opinion i would say that Shawn Michaels was the face of the company still in 1997 as he was the face of WWE from WrestleMania 12 through to WrestleMania 14.