I wouldnt classify Taker-Mankind as a Cage match. A Cage match is different from a Hell in a Cell, there's 2 ways to win a Cage whereas there is only one way with a HIAC match and HIAC matches has a rep of where both guys destroy each other but Cage doesnt.
Anyway my fav Cage match would be a tie in between Rock vs. Mankind vs. Ken Shamrock & Austin vs. McMahon. I'm biased though because both took place in the Attitude Era which is the era I grew up watching wrestling and I liked the old blue & black square holed steel cages better than the modern day WWE cage.
Rock vs. Ken vs. Mankind was different than any other regular 1 on 1 Cage match, it featured 3 people of course which made the match more challenging, unpredictable as to who would win & exciting. It had some pretty hilarious moments in there with Mankind and it had a good ending to the match with Mankind looking like he would win when he was climbing the cage only for Rock to pin Shamrock to steal the win.
Austin vs. McMahon was intense and showed that their hatred was beyond just a Cage match, the two started fighting outside the Cage, McMahon took that bump off the cage through the Announcers Table which Stone Cold mentioned in his What?!?! DVD that McMahon didnt need to take the bump but he did for the sake of entertaining the fans and even though he was injured & couldnt carry on with the rest of the match Austin brought him back into the Cage cause the match never officially began as the fight took place outside not inside which was a good twist & a lot of people loved as it was there opportunity to see McMahon get more damaged than he already was and whenever Austin was about to leave the cage and win, he came back into the Cage to kick Vince's ass more when he kept flipping him the bird to that unexpected debut of Big Show coming through the ring mat into the ring, tossing Austin into the cage walls like a rag doll forcing one of the cage walls to eventually break open and drop Austin to the floor to win, it was an awesome match.
Out of the two, I would go for Austin vs. McMahon more.
On a small note, my fav endings to a Cage match would be Ken vs. Rock vs. Mankind as mentioned above & JBL vs. Big Show's cage match, it was a clever tactic on JBL's part, crawling underneath the ring to the outside to win after getting Chokeslammed off the top rope through the ring, very unpredictable & smart.