If you want high resonance with a bass sound. This might come into play.
just use 2 filters in parallel - 1 for high resonance and 1 for more bass!
Outputs. When dealing with a multi-mode filter, how are the outputs structures. Some modules put all the filter types on separate output jacks and all filters are simultaneously available. Others use only one output and the user selects (usually on a switch) which filter feeds the output.
and often somewhere in between - see Doepfer Wasp and SEM filters, for example!
Input (levels). Some filters have input level controls. How hard your signal hits the filter can alter the sound significantly. So an input level control might allow you to adjust things to your taste.
always a good thing - but an amplifier module (or a vca that actually amplifies instead of attenuating) in front will also do the job
Modulation. This can range from simple CV control over the cut-off point or you can get into modules with multiple controls including the afore mentioned FM control (linear and exponential), 1/V Octave tracking, CV over resonance, and even some exotic controls like ping, mix levels, even control over filter type.
-- Ronin1973
more modulation is always good!
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities