I find rclone cache slower at scanning in new files and slower start times.
Plexdrive4 = cannot stream 4K files due to bandwidth limitations
Plexdrive5 = can stream 4K, but there are two bugs, 1 - Missing files, 2 - Whole files are downloaded when not intended, lots of bandwidth used
Rclone cache = can stream 4K, slower at scanning files into Plex
And of course you have to remember that Rclone is SUPER active in development and fixes. Where as Plexdrive has been dead for over a year, zero bug fixes.
From this you can decide which is best for your needs.
I never noticed issues streaming 4k on plexdrive4 or plexdrive5 as they both worked well for me.
I don’t think there is a bug on whole files either as I’ve used plexdrive5 for quite some time. That’s more likely plex settings gone wrong or misunderstanding them. Plexdrive5 just grabs what you ask
For me in terms of speed, cache is the slowest to start due to the how the workers are coded. Plexdrive next and vfs-read-chunk-size is the quickest. The difference between the two for me in is the 1 second so both are very nice.