Correct me if I am wrong but I always felt Survivor Series 97' Bret and HBK were both heels. Bret was all pro Canadian whiny bitch and Shawn was all degenerate trash. I mean I understand you can call them tweeners(and I personally liked both characters) or whatever but as HBK went into Wrestlemania 14 he was definitely more a heel, and Bret was heel all that summer into Summerslam and personally into that match-up. To me that is the best example of that.
Face versus face, for me was HBK vs. Cena and as mentioned HBK vs. Taker.