I think we need to understand firstly, what is tasawuf? If we come to a conclution that it is sitting in a corner with a tasbih at home, in a khanqah, in a group or alone then we dont know what tasawuf is. infact to choose which is beter between tableegh or tasawuf is really foolish. because the two have to move together or atleast the one should inspire the other. tasawuf is largely to do with purification of the heart, you need a pure heart to do da'wah. so without tasawuf you will be comming short in your tableegh too. & calling to Allah is also part of tasawuf, so why try to devide the two.