I've used both FreeNAS and OMV, and find the OMV community more welcoming and helpful than the FreeNAS one. The FreeNAS community has organized itself with the intent of focusing exclusively on very specific very corporate use case. If you don't fit they're use case, you are bad and should feel bad. OMV on the other hand is much more open and willing to help people use adapt it to their own needs.

With the notable exception of ZFS vs EXT4, they underlying software appears to be the same, which makes the community distinction every more cogent.