Music + Plex = Labour of Love 
I’ll pass some of my own advice, ignore or take it as you will. I’ve 1167 artists, 9198 albums and over 133k tracks all of which are tagged using musicbrainz picard and matched 100%.
Read this → [HowTo] Configure Plex to use embedded metadata (music) if you have not already. It’s invaluable and especially important when using embedded tags.
I really struggled with popular tracks when I started using plex due to how the plex scanner works and thus how is builds the popular tracks list. I wrote this long winded procedure [HowTo] Configure Popular Tracks Section to Prioritise Albums over every other release type! to get around its short comings regarding multiple tracks with the same name across multiple album releases (album vrs live). You may or may not find it useful.
As your using musicbrainz picard to tag, this filename renaming snippet might be helpful to you (its what I use myself):
$if2(%albumartist%,%artist%)/
$rreplace($if(%albumartist%,%album%),[:"], - ) ($left(%date%,4)) [%releasetype%]/
$if($gt(%totaldiscs%,1),%discnumber%,)
$if($and(%albumartist%,%tracknumber%),$num(%tracknumber%,2),) - %title%
and I also set the following within the scripting - enable tagger scripts options:
$set(artistsort,%albumartist%)
$set(albumartistsort,%albumartist%)
$set(albumsort,%album%)
$set(date,$if2(%originaldate%,%date%))
Again, I find these useful but your own mileage may vary depending on your use case.
