Although it only has one knob on it - and not much else, to be frank - Audified's VocalMint Compressor plugin actually contains three pre-tuned compressors (plus an analogue-style valve stage) that are specifically designed to work on vocals.
Inherently simple to use, VocalMint gives you a “virtual signal chain” that comprises a smash compressor, valve compressor and multi-band compressor. Collectively, these are designed to resolve problems related to the human voice.
The valve circuit adds some subtle EQ shaping, too - not enough to get in the way of your own EQ processing but enough to make the track sound more open, apparently - and you can also open up the interface to gain access to a few more controls.
VocalMint Compressor runs on PC and Mac in VST/AU/AAX formats and costs $79. There’s a demo you can download, too; head to the Audified website for all the details.