90% of them.
As a matter of fact, on my most recent mixes, the only 3rd party plugs I used were... Waves.
EQ and Compression are the two things I use the most - and most of the time I use my native plugs for that. Occasional exception for EQ - IK's Pultec.
Occasional exception for Compression - IK's Fairchild (though I'm getting better at dialling what I want using the VariMU mode of Logic's comp), Waves CLA compressors.
Others - IK's British Channel, and, even more rarely, reverbs - Lexicon, IK's CSR and Valhalla.
Most used/essential 3rd party: Waves tape emulations and L1. That's the only ones I've been using lately.
Which is why I guess I have had my plug-in acquisition syndrome well under control for a while. I'm only getting stuff that my basic set of plug-ins don't cover, which isn't a lot. EQ's and compressions don't really interest me, nor reverbs.