I Have Done Both B.t. & Fiitjee.
The following are my thoughts on each:-
B.T. :-
1. Highly Relevant.
2. Builds your Basics.
3. Great Study Material
4. Errors are very rare.
5. Test Series is not advisable.
Fiitjee :-
1. Highly Irrelavant
2. Not Useful If You Are Not A Born Genius.
3. Test Series Is Tough But Makes You Ready For Facing All Situations In The Exams.
4. Error Prone Solutions.
Final Advice:-
B.T. Study Material & Fiitjee Test Series.
RATE ME PLEASE.