hey ronak ...
now this is a question which might have many answers ...u know the reason..everyone has a personal opinion ..i don't want to favour any particular material in the public but will try to clear your query by pointing out the plus points as well as the negatiive ones about both thye materials ...after that its up to you , whom do you chose..
so about fiitjee :
well fiitjee has an ok physics ... not bad .. but somewhere i feel it doesn't stress on concepts .
fiitjee's physical chemistry is good... it has got some nice problems for practice
fiitjee's inorganic chemistry isn't upto the expectations at all .. you can read it but you can't cover the whole syllabus using it
fiitjee's organic chemistry is again so so...
fiit jee's maths ...yeah they have got some wierd maths ...you know the kind of questions that you imagine only in your nightmares ..they are there ..but again they also cover the basics.. so maths can do..
about brilliant:
brilliants biggest plus point is its inorganic chemistry ...its reallly good ... it quite comprehensive
brilliants maths is also above average ....
brilliants physics again is ok types ..not too good ..and not bad at all..
so in all i can say that both of them are good ...if you follow them properly with proper combnation of books and all ....