I have and use both a lot.
70-200 is a workhorse I use on the job a lot, sports and events, situations where a zoom is pretty necessary.
I got my 5DII and the 135/2 at about the same time. It was one of my favorite focal lengths for portratiture when I was shooting film, so I knew it would see plenty of use as soon as I got a full frame camera again. An 85mm had served well on my 1.6X cameras for years (still does, and is useful on FF too).
70-200 is a fine lens, especially considering it's a zoom... But it's big, heavy, intimidating and, well, it can never do f2.0.
I much prefer to shoot with primes whenever possible, the zooms stay in the car or at home unless it's a job that demands them. This is just a carryover from learning to shoot mostly with primes a few decades ago, when the majority of zooms were crap. Today there isn't nearly as much IQ difference, but primes often still win out slightly in terms of IQ and in some other respects.