Some audio examples of what you mean by not sounding nice would help.
I would suggest that you go through the presets for each of the synths to find bass sounds that you like first and then create/choose other sounds that match/work with them.
You are expressing a dissatisfaction with sound choice which is a sound design issue. Sound design is not just about creating new sounds, but integrating existing sounds to make a cogent whole - spend more time finding sounds that work together initially rather than hunting for them later.....