I’m thinking of getting a new PC case, and when I take my current PC apart I’ll obviously be reapplying thermal paste, my question is if I should just use the same paste or buy something better, or does it not make much difference? The thermal paste I have applied now is Noctua NT-H1, it came with my cooler.
When I say performance, obviously I mean thermal performance.
The best paste is probably thermal grizzly kryonaut, though differences in thermal performance between pastes is relatively small. The Noctua paste you currently have is also a top performer so the difference you will see in thermals is even smaller. Proper application (making sure you have sufficient coverage between the cooler and IHS) is a bigger contributor to thermal performance when it comes to paste.
like @Tushar22 said, and yourself mentioned Grizzly Kryonaut and Noctual NT-H1 are almost the top best ones you can find, other than that CoolerMaster Mastergel or ARCTIC MX-4 2019 Edition. but in my opinion if you have Noctua left, use that, its not inferior than anything. check out the followin link for more options.