Boiling it down - if you are editing and creating content you'll be much happier with 6-8 @ 3.4-3.6Ghz cores from an E5-1650/1660/1680. For 'bang for the buck" analysis remember that going from 6 cores (1650) to 8 cores (1680) more than triples the list price (33% potential performance gain for 300% more $$$). Street prices vary, but E5-1650 is the sweet spot here.
If you are encoding/recoding/transcoding/compressing/rendering/etc and doing it on multiple streams at once you'll be happier with many medium speed cores (20-40 cores @ 2.2Ghz. But remember - those are also jobs that that you can queue up and go to bed. So - unless you are doing industrial scale production it might not really be worth it. And you can set up 2x systems with E5-1650 for less money than one dual-proc E5-2698/99 (unless you are willing to go with ES chips, of course). That way you can have one system for editing and one encoding away 24x7.
In practice, you'll find production houses with high-clock/low core workstations on the artists desks backed by a server room full of core working as a render farm for post-production. You probably don't need that in your home/office but the underlying principle is the same - clock for editing, cores for encoding.