I like the
http://www.stillwellaudio.com/ plugins. I think they still have some free versions. AU and VST. They tend to belong in the vintage repro camp. Most of them being Neve, SSL and other such classics. But they sound better to me than a lot of plugins that I've paid more for.
The Waldorf trio of plugins; Attack, D-Pole and PPG have been part of my arsenal for a very long time. These are not warm vintage virtual instruments. They are kind of edgy and awful and mean. You could pretty much write a whole song using the Attack drum machiner and PPG synth. I have. The Dpole I dont use for a filter, I have better. I do like it's ring mod a lot though.
I also own one of those UAD boxes, and use it for an EMT reverb, Helios EQ and the bundled plugins.
I used to use a ton of other plugins, but the last few years I've gotten more into accomplishing things in the analog realm as much as possible. Which isn't really that expensive if you are only recording one thing at a time anyway.