I got jee advance prep sc rank 1070 and it says i am qualified where should i get seat or i go with mains rank

Try with both your scores through JoSAA counseling. If you're getting an IIT definitely you should go with advanced score, or else you can use your JEE MAINS score to get NITs, IIITs, and GFTIs. Definitely it depends on your MAINS score too, which you haven't mentioned. It also depends on whether you're willing to sacrifice IITs for the course of your choice in NITs. So my answer would be, use both scores, and select the course and college according to your preference, and through the rounds, you will be allotted a seat, according to your cutoff. All the best!