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.
Large databases and complex queries or video streaming definitely will benefit from higher clock speeds from single core performance. But if you plan for multiple users using your services at the same time, then multicore benefits will outweigh single core performance.
So if you are the only user than single core it is, but if you have multiple users or run multiple docker containers than you reach a bottleneck quite fast, where background services will compete with each other.
Usually “a server” runs a lot of different things and programs. Multicore is especially beneficial in that scenario because even if a certain program does not support multicore processing, the os will just run “the other app” on another core.
So the concept of which app can use multicore processing is mainly relevant for desktop PC’s that run “one big app”.