I assume you are referring to study material provided by coaching centers. VMC is known widely in North India for its top notch study material and correspondence program. You can't go wrong with VMC material. If you are looking for material besides coaching centres standardized sources, Halliday for Physics, Arihant for Chemistry and ML Khanna for Maths should be fine. Use HC Verma for Physics if you find Halliday too incomprehensible.