Thanks for sharing your query because most of the time it's a common confusion in selection of the reference books for mathematics.
My vote goes to XII (CBSE) PART 1 AND 2 by R.D.Sharma because of following features:
(1) rarest mistakes and errors in it.
(2) almost complete NCERT is covered through solved examples and unsolved problems.
(3) large number of solved examples with detailed solutions and very exhaustive practice exercises covering all varieties of question as per the requirement of CBSE.
(4)content coverage gives ample scope for developing good basics required in competitions.
(5)MCQs and VSQs at the end of each chapters are the best part of the book, although having some errors, but the manageable ones.
I am a premium promoter for this book of CBSE since last 15 years , but i will request the community members to share their views in this regard, quite possible of the availability of some other good NEW book in market.