Subtractive is foundational: start with a rich waveform and filter it down. Learn this first. Wavetable scans through a table of waveforms, and modulating the scan position is what defines the modern EDM and dubstep bass sound.
FM (frequency modulation) uses one oscillator to modulate another’s frequency: integer ratios sound harmonic, non-integer ratios give metallic bells and clangs. Granular chops sound into tiny grains for textures and atmospheres.
You don’t need all four. Get fluent in subtractive, add wavetable when you want movement, and treat FM and granular as flavour.