Are there any particularly good commercial plugins available for Linux?

Vital is a spectral warping wavetable synthesizer with drag'n'drop modulation workflow and animated preview of the synth's inner workings where needed. Comes with many modulation sources (including audio-rate), MPE support and FX chain.

u-he makes creative software synthesizers and effects.

Open-source subtractive-hybrid synthesizer formerly sold commercially as Vember Audio Surge.