I use tdarr for my large scale conversions to AV1 but I use shutterencoder for everything else. It’s like handbrake but friendly for working in large batches and the UI is really nice https://www.shutterencoder.com/en/ It will add H265 to the end of the name too
If whatever you’re doing works with av1 then I’d say go for it. I do AV1 for Plex since all of my devices can hardware decode, however I keep my own videos at h264 software encoded (for smaller filesizes) since Synology photos doesn’t support AV1.