Isca book confusion

Sir/Mam I have been studying ISCA from manish valecha, but after 4chapters, I am finding it a little difficult to comprehend. But after reading the recent discussions regarding Manish Valecha to be best, I have some doubts. I have gone back to Dinesh Madan. Please recommend if I should do the same from Valecha or Madan I am aiming for rank and studying all the subjects with required efforts and dont want to miss out on ISCA. please suggest the same to me Regards