Solid Explorer, since I can mount an SFTP volume using keyfile authentication.
The only thing I don't like is that it uses its own file encryption system instead of a more open solution like Cryptomator. I know Cryptomator exists, but I can't access SFTP volume using keyfile authentication with it..
Also, one of the drawbacks is that it needs Google account to be added to the device to access the drive.
MiXplorer can directly use the browser the get access to drive, thus making it more FOSS friendly ROMs.