I use Nextcloud only for the sync but I think it is too clunky and it uses too many resources, but I haven’t found anything else that syncs from Android and iOS. After they are sync to Nextcloud I sync them somewhere else for permanent storage. I wish there was an easier solution.
As long as you have Plex Pass, hardware transcoding is extremely good with moder QuickSync Intel processors, and specially good if you run Linux.