Carbon Electra from Plugin Boutique is a 4 oscillator subtractive synthesizer with an aggressive sound and affordable price. Nice filters, build-in effects and step sequencer makes this a very versatile yet easy to use synth. Current price is 71€
Hybrid 3 from AIR Music Technology contains two subtractive synthesizer engines each with 3 oscillators, 2 filters, 3 LFOs, modulation matrix and step sequencer. Hybrid 3 comes with 1200+ nice sounding presets including some amazing evolving sounds.
Hybrid 3 is bundled for free with certain MIDI keyboards, audio interfaces etc. Otherwise the price is currently $149,99.
MPowerSynth from Melda Production is a versatile synthesizer with nice sounding oscillators, advanced filters and effects. A unique feature is the smart randomization system, that allows for endless inspiration.
Roland Cloud is a cloud based service where you will find all the legendary Roland synthesizers like Juno-106, Jupiter-8, SH-101 but also more modern synths like System-8.
Serum from xfer Records is an advanced wave table synthesizer with a very high sound quality. Build in wavetable editor, powerful effects rack and morphing oscillators make this a powerful tool for sound design and a very capable synth.