Currently the Frequency Filter modifier for oscillators creates nasty ugly ripples in the waveform which can be an issue for anything that uses the amplitude of the signal, like FM or RM/AM or distortion, and visually it’s difficult to gauge how it’s adding to other waveforms if there’s layering in the oscillator.
Bessel filters better preserve the wave shape of signals, which seems like it’d be important for a wavetable synthesizer what relies on manipulating wave shapes.
I don’t mean to suggest that the current filter should be removed and replaced since there may be some quirky sounds that end up changing, but adding Bessel LP/HP/BP as additional styles would be nice. Naming the styles to convey the important characteristic in case someone isn’t familiar with, say, Bessel vs Butterworth, could be done like… default is Sharp and Bessel is Smooth? That’s how it’s done in FL Studio’s equalizer for LP/HP and I think it works well enough as a description there.