Picard is probably the most popular tool for this, but a problem with any auto-tagger is that you may disagree with the genre selection. Because the data is all crowdsourced you also see inconsistencies… Like “Hip-Hop” and “Hip Hop” both in use. Either you live with that stuff… Or, you do it yourself.
2500 tracks isn’t actually that much to do manually. Chip away at it with a great tool like mp3tag, and once you are caught up, do new additions as you get them.
Someone here said:
It does tend to work better with albums, I’ve mostly moved to getting an album when I’ve wanted a single song…
This is so true. Loose single tracks are a pain in the ass too. Try to get full releases.