Reili
I think Bleach would be good. The original reason MC didn't choose Bleach is gone, and it'd be hilarious to see what chaos would MC cause with his dual Zanpakutos and Bankai. Also, since Tengoku's Bankai should be MC's strongest ability right now, either Bleach (best choice), or Danmachi are most effective choices for strenghtening himself, Danmachi being more of an all-around increase, while Bleach strictly spirit techniques, and soul and Bankai.