Besides the great Synthesizer Suite created by Rui, I've had very good performance experience with Yoshimi.
So much for general purpose synths (which I think is why you ask).
Then for more peculiar sounds,
Whysynth is a DSSI FM-type synthesizer with very good performance and very interesting presets.
ADLMIDI and OPNMIDI emulate vintage Yamaha chips like those of the Sega Megadrive (Genesis) and consume few resources.
Amsynth is also light.
Calf monosynth and Calf Organ also have excellent performance and very cool presets.
These are the ones I have installed. I prefer to have few and reliable ones.
Besides the great Synthesizer Suite created by Rui, I've had very good performance experience with Yoshimi.
So much for general purpose synths (which I think is why you ask).
Then for more peculiar sounds,
Whysynth is a DSSI FM-type synthesizer with very good performance and very interesting presets.
ADLMIDI and OPNMIDI emulate vintage Yamaha chips like those of the Sega Megadrive (Genesis) and consume few resources.
Amsynth is also light.
Calf monosynth and Calf Organ also have excellent performance and very cool presets.
These are the ones I have installed. I prefer to have few and reliable ones.
This website has a list with almost all the synths available for Linux:
https://linuxsynths.com/index.html