[Marsymars]

SnapRAID is awesome, it's been bulletproof in recovering multiple failed drives for me, but note that you have to have your sync and scrub operations appropriately configured to get bitrot protection.

[QuiEgo]

I have had good experiences with SnapRAID as well. I use this script to run it (in a Chron job), which is highly configurable:

https://github.com/auanasgheps/snapraid-aio-script