I am in class 10 living in Dombivli.I don't understand which class I should join for JEE Preparation.

Allen is best as compared to other inatitue for iits

All these coaching institutes are top institutes. You can choose any one of them according to your comfort or location. Coaching classes can only give you direction to get good result you have to work hard to get desire result. It's totally depends on the student whether he/she is not able to crack the exam not coaching institute. To score good marks in JEE exam make sure your basics are clear. Build your concepts strong. So, that you can easily do tricky questions. Before starting your preparation you should be aware of the complete syllabus. important topics and exam pattern. Refer previous year papers to understand the exam pattern and level of questions. Once you complete one topic solve MCQs related to them. Give importance to NCERT books as syllabus is based on them. Practice as much as you can. Solve complete mock test series to check your performance level at regular interval of time. All the Best for your Preparation!!