Threadripper is a good compromise between speed and money, so go for it. If you can afford it, always take the faster variant - turbo speed still is the dominating factor.
Mind, DELPHIN parallelization benefits most until 6-8 Cores, after that the increase in speed is not as great (not all cores can be fully utilized). If you want to run several jobs in parallel, more cores are better (though mind the memory bus bottle neck).
We have a threadripper 1950x which is ok for most of our simulations our, the 2950x will do good as well (with 16 cores, 32 threads). Also, these are 180W CPUS - newer Threadrippers take 280W or more (but have more cores, of course).
NVMe is a must, i would say. Normal jobs, that you'll need a highend workstation for, are not really output-driven (unless you do optimization stuff, where you run thousands of small jobs to see the progress of your parameter optimization - here, ssd-speed rules). You can take the "evo" or consumer variants - the expensive pro variants are really not needed since simulation workstations are not database servers.
A raid system is IMHO not necessary for simulation jobs - if the ssd crashes, just reinstall and re-run the simulation (no backup - no pity
). Normally, pre- and postprocessing is done on a separate machine anyway. Save the money and put it into the CPU.
As for overclocking memory, I would go with regular normal brand memory chips - the overclocking ram modules with head spreader aren't really worth it (even put the system at risk).
Lastly, take a good case with decent ventilation, we have a "fractal design define r6" - quiet and very good air circulation. As CPU cooler we have a CORSAIR Cooling Hydro Series H100i v2 - which works very well so far. A large CPU fan should be ok, too.