As Nico said it depends on what you’re doing. Generally as far as I know you benefit more from a faster CPU when you have a long chain of processing- meaning the signal flows from one process into the next, then another, then another and so on in series. Having a lot of processing in parallel often will load more cores.
I asked you to search because I even started a brand new thread a while back because people keep asking this question and never seem to do a search on the topic. For benchmarks we currently have mostly ones for AMD’s previous generation 3xxx-series. You can find DAW specific benchmark results at SoundOnSound and Scanproaudio. The test is called DAWbench… Find the latest article and you can then compare different CPUs.
The test has a “DSP” part which is basically just a heavy plugin, and then it has a VST instrument part which is a combination in which the list how many voices can play back from a sampler. In both cases they increase the load until there’s crackling.
The latest 5xxx-series CPUs from AMD should be significantly better than the previous generation btw.
Then you can read the following thread starting at the end:
The “today we build our studio pc” thread - Gearslutz
If you don’t find what you’re looking for you can ask for recommendations in that thread for either Intel or AMD.
As for PCIe lanes the “consumer”/“prosumer” lines from Intel and AMD have roughly the same amount of lanes with the exception of the latest AMD generation supporting PCIe gen 4, which has higher throughput. So hypothetically you could bottleneck an m.2 NVME SSD drive on an Intel setup but likely won’t do that on an AMD setup. If you want more lanes though you end up with what’s more of a “workstation” platform from either company, and that’s going to be pricier and generally lower clocked CPUs. In addition to more lanes though you can get more cores, more memory channels, and some other goodies.
My hunch is that on the AMD side you really should be looking at a 5xxx-series Zen 3 Ryzen CPU, not previous generation. I think Intel just made public a new lineup which could be competitive in price, but that also means that AMD might respond by lowering their prices - assuming they can keep supply up. Right now CPUs are a bit expensive…