Well, both R D Sharma as well as R S Agarwal are derived from the same source i.e. NCERT book. So there`s not much to differentiate between the two. However, based on my personal experience and many surrounding real-life observations, I feel both have their own benefits as well as flaws. R D Sharma is more driven towards conceptualization while R S Agrawal promotes more of slow paced gradual learning. If you have sound fundamentals gained through NCERT, you can start solving R D Sharma problems but with R S Agrawal, you have the liberty of starting from scratch. The problem difficulty level, I believe, is also more pronounced in R D Sharma than R S Agrawal.
To summarize, if you have plenty of time in your hand and like solving humongous amount of almost similar question before jumping to next level, R S Aggrawal is the go-to book for you. But if you have sound fundamentals but relatively less time and you want to cover all aspects of a chapter within limited set of questions, R D Sharma will help you more. Ultimately, it`s a case of personal preferences.