Obviously IIT is much better option if you want to pursue your higher education in India otherwise SAT.
SAT examination is given for admission into various graduation courses into United States. You need to go for JEE-Main and JEE-Advance examinations to get into IITs. Both have a different life and as far as Indian Education is concerned, being a part of IIT is already a very big achievement and you get some great job placements and opportunities after being a part of IIT.
Refer to the links given below for more detailed information :-
I hope this information helps you.
IITs are the best Institutes in India for pursuing Engineering. JEE Advanced is the exam considered for admission in various IITs.
SAT is an exam conducted for admission into various courses for several Universities of the world. World's top universities accepts SAT scores along with several other criteria for admission.
If not for financial restrictions, pursuing degree courses from World's top universities is the best option.