This may be naive but I am unsure how you tell what applications benefit most from single core performance vs multi core performance. I feel like upgrading my server to a processor with higher single core performance will benefit the “snappiness” because the CPU utilization percentage sits at such a low level. But that may not even make sense.
It all depends on what you do with the box, how the applications you run utilize the cpu (single vs multithreaded/multiprocess but also stuff like cpu cache utilization. if you profile the workload that you want to run (see if its cpu, memory or io bound for instance) will help you in figuring out what works best for you.