I say The Undertaker, coz even though HBK hasn't held the world title for seven years, he is a Grand Slam Champio. The Undertaker isn't a Grand Slam and even Triple Crown Champion. Also, during HBK's first title reign, he held it long enough for 8 months. While The Undertaker has never had any long reign as world champion. Not only that, Undertaker also hasn't held WWE Title for 7 years (he just won the World Title), also he has never held the Spinner Title belt. So, The Undertaker deserves more, no matter how long his reign would lasts, I just want to see Undertaker won the WWE Spinner Title belt.
WQ: Yes, for sure. Triple H won't be able to handle the Legacy and kept getting screwed out of the title for two straight PPVs (The Bash and Night Of Champions). So, at Summerslam, DX will reunite to take on the Legacy.