I would say that the modulus is the most versatile. It just seems to cover more tones than the others. However the thumb has a tone that is all its own and although the modulus could cover that style itll never nail the tone.
Now I have always wanted to actually own a Dolphin but would probably pick a thumb over it if I could only choose one.
So I guess what I'm saying is that out of your four id take the quantum if it were to be my only bass.
The flea bass?? If that were a serious contender for you Id also look at the Modulus or a Lakland 44-02.
The thumb?? if youre considering this I would also consider a higher end ibanez soundgear... theyre very good instruments and the neck is considerably faster than a warwick.
this is all just my opinion though... if youre spending money be sure that your opinion is the only thing you use before you throw down your cash
