If I may weigh in (on both the pitch detection & 32/64 topics):
I have tried all three of the aforementioned objects, and personally found [helmholtz~] to work best for my uses. I can't say I was extremely scientific in my comparisons, but I generally got the sense that it performs a bit better than [sigmund~].
When I first began migration from extended to 64-bit vanilla, all of the 32-bit externals I was using needed to be replaced, and [helmholtz~] was the one I missed the most. I replaced it for a while with [sigmund~], but eventually I went & compiled a new [helmholtz~] from source against 64-bit vanilla, which is working fine.
Now, as for comparing performance of 32 vs 64 bit Pd in general (very much FWIW... I'm on MacOS, not Windows, and I have no technical knowledge to back these observations up): a couple years ago I did test my most CPU-intensive patch in both 32 and 64 bit vanilla, and found a modest ~15-20% CPU performance boost (according to the load meter) when using 64-bit. I remember seeing some discussion of this on the Pd-list a while back, it might have been this thread. I did not compare memory usage between versions, so I can't speak to that.