if we are planning to invest , we have surplus funds which are usually parked in Savings Bank accounts , which offer a return of 3-4 % . From this we usually opt for sip's . However stp's do the same function as sip's , but at the same time they earn @ 8-9 % which is so much better than the 3-4 % earned in an SB Account during the waiting period . So stp's are definitely better than sip's , unless we are in the salaried middle class ,squeezing out the instalments every month .