I like both but prefer Into Darkness.
I watched TWOK about 2 months ago and while it was still awesome it felt dated and kind of cheesy, IMO. I still think RM was great, but I think BC was great in his own right as well.
And I am a huge fan of the Augment/Khan storylines. I loved the books by Greg Cox and how they included Gary Seven (one of my favorite characters) and his work during the Eugenic Wars.