5960x for the solder.
Although in terms of how things are phrased the 6700k with the IGP and newer features would make more sense as a hand down or secondary system down the line.
What makes this also a tough choice is hypothetically I'd prefer a SFF build and itx would limit the 5960x to only dual channel so I'd have to go m-atx at the smallest.
Do we get free memory as well?
Are there any examples of games that would actually favor a 6700k due to the faster cores over both the more cores and larger cache of the 5960x? Focused in terms of actual play ability of minimum and lower end fps as opposed to bench marking higher in terms of avg fps well beyond 60? This would the only usage I can think of that the 6700k could win out at in terms of performance but are there examples?
Otherwise it seems to come down more to whether or not you feel the newer platform has more advantages.