For ESXi you mainly want iops.
In the past this meant Raid-10 alike storage with as many raid-1 as possible.
With NVMe like the P3600 you have a lot more iops so this may not be as relevant. With ZFS you have additionally a large rambased writecache and a huge readcache with enough RAM. Basically its a question of how large the pool should be and how much money you want to invest and how many pci lanes you can offer.
I am in the same situation, thinking about massive NVMe storage solutions. I am evaluating the new socket 3647 boards due the huge amount of pci-lanes, U.2 NVMe to use quite a lot of them and the new Intel Optane NVMe as they halves the latency even of a P3700 with around 8x the iops. I have just ordered a new 900P NVMe that is in a similar price range than the P3600 but in a whole different performance region, especially as trim or garbage collection is no longer needed as they address the NVMe more like RAM.
For the hardware, I check SuperMicro to use the appliance/OS of choice.
My next systems are like
a Supermicro | Products | SuperServers | 2U | 5029P-E1CTR12L and I wait for a similar case with U.2 bays instead of SAS. Even such a single board is capable for max 9 nvme beside 10G and the SAS controller. In the meantime I will use U.2 and use 2,5" slotadapters to mount them inside.
btw
Care about crash resistance, redundancy/ Raid/ Snaps/Data security.
Even with a daily backup you have work to rebuild and a backup is like old bread, always from yesterday. And without a modern filesystem with checksums you cannot be sure that a backup is valid.