Given the choice of more slower cores or fewer faster, then I’d lean towards the fewer but faster, so long as the cpu has enough cores to start with. A fast i7 would be my choice, maybe i9 if the budget ran to it, but not if that meant a major slow-down in processing speed.
If the load being sent to one core/virtual core is more than its speed can handle adding more cores won’t solve that problem.
Large numbers of cores seems to mostly benefit video/film editing and rendering, where a lot of time can be saved by using cores in parallel each processing a chunk of the video and overall cpu speed matters less because the rendering is off-line and the extra cores more than compensates for the lower speed of each core.
DAW thread scheduling improvements and general software optimisation of DAWs and plugins may change that situation of course. In computing there’s always something a bit better coming along soon, so there’s never an ideal time to buy anything.
Like a lot of things in the world of DAWs, especially Windows DAWs, the only way to find out for sure what works best for your personal setup is to try it and see. Which is fine if you can afford to build/buy a bunch of differently configured computers for evaluation purposes. Failing that the best strategy is probably to look at what other people’s experience has been while paying attention to what competent professional DAW builders, like e.g. Jim Roseberry on this forum, say and do.