FreeNAS Scale vs Unraid specific use case

Hello all I’m looking to build a new home server but have a few questions.

Scope/use case:

I’m looking to build a new NAS that can run Plex with a GTX 1050 ti for encode, supports offsite backups, encrypted personal folders with remote access, maybe run some linux VMs, possibly a network drive for steam library. 2.5Gbe and 10Gbe networks is already in place so that’s not an issue.

Hardware/software:

Looking at a Ryzen 5900x due to the ECC support and low cost. Running an AsRock Rack X570D4U-2L2T with 2x32GB (64GB) DDR4 3200MHz ECC.

I was looking at older LSI cards to flash into IT mode to host my drives vs the onboard SATA controller. From my understanding this tends to be a more reliable way to do it along with flexibility. Plus the convenience of going from SAS to a SATA backplane in a chassis.

SSD cache: not sure what drive/s I should go with here and best config for it. I rarely transfer file/s over 100GB. Can this be used to cache specific files as well or just Read/Write cache?

HDD: I was looking into getting 5 or 6 of the Seagate IronWolf 8TB NAS ST8000VN004-NE.

I know Unraid supports Plex docker with GPU transcoding with a few steps due to the “better” VM/Docker support but I understand FreeNAS can have higher performance plus better data integrity.

Having two parity drives seems like it’d be fine for me and expanding storage doesn’t seem like a necessity anytime soon. So I’m thinking FreeNAS Scale but the simplicity of Undraid is nice.