The best bass synth (if your actually going for bass synth rather than a "******** saxophone" sound) would be the EHX BMS imo.
"Retarderd saxophone" sound, I'm intrigued.

Did you mean that you get that from the Boss SYB-5 (or SYB-3)?
If so, on what setting? I'll try it out in the local music store.
A EHX BMS they don't have to test out. Can you get a less retarderd saxophone sound from that?
My ideas on BOSS pedals: about half their pedals are great, and about the other half or bad and have better alternatives. (The price is also something to be considered.)
What I think are great pedals: bass equalizer, limiter/enhancer, compression sustainer, MT-2 (on guitar but in some ways it works on bass), the DS-1 and OD series are great on guitar but not on bass, the EQ-20 is great...
What are terrible pedals: the ODB (a much better alternative is the Ibanez PH-7 as overdrive), the bass chorus,...
It all comes down to the sound you prefer.