I have a choice of buying
E5-2560 v4 or
E5-2630 v4. The former has a TDP 105W while the latter has a lower TDP of 85W. If price was not an issue which is a better choice?
It looks like you made a typo above, saying "E5-2560", but linking to the E5-2650. I'm assuming you meant the latter.
If price is not an issue, and running cost is not an issue, the 2650 clearly should have the performance edge due to the larger cache. Larger CPU cache is almost always better for compute performance, if all other factors are equal (e.g. technology generation, clock, bus performance, etc).
A quick scan of the Intel spec sheets says to me that the 2650 is pretty much the higher performance device in almost every regard (cache, bus speed, cores, threads, memory bandwidth, etc). It has a slightly lower "turbo" clock, but that seems likely to be insignificant after all the other benefits. It's not necessarily a huge difference in performance between them, but the 2650 clearly looks like the higher performance device, although both are essentially minor variants of the same processor. Whether you will actually get sufficient benefit from the additional performance (to justify the extra cost), that's something only you can answer (but both science and video can be quite compute intensive, so the marginal benefit may be useful to you).
Intel's site lets you do an easy side by side comparison of them:
http://ark.intel.com/compare/92981,91767
On a pedantic note, what you describe is most certainly not a NAS (network-attached storage). It is a general purpose server providing both file storage and compute/processing services. A true NAS only provides file (and maybe print) service, and nothing else; certainly not something that would run lots of jails/VMs.
