fiitjee classes

aakash academy

narayana iit academy

have proved to get best results from delhi

Basically I wont endorse any coaching centre as they are a means of helping you learn. It will depend on how you work and study so any one is good as long as you are dedicated enough. Some pointers when joining an institute -

Check the distance from your house. Right now it may be fine but when you get in class 12, it will be really tough to go and come and make time to study. So advisable to pick one near your house

Find out how the syllabus is taught. Is it in tandem with the school's? Many dont check so the school syllabus goes in one direction and the coaching centre's goes in another. Then you will face trouble as you will find it tough to score equally well in both. The board exams are equally important.

Check the faculty credentials, timings, test modules and schedule, support in case of doubts etc.