Many students get confused about whether to give online or offline exam. There are many advantages and disadvantages of both the exams. I'll tell you about both then you can decide for ypurself.
Online exams
Pros
1. You can concentrate on your own work without caring about whats going on others computers.
2. You can answer faster as you don't have to bubble answers which saves tons of time
3. You have to pay less fee than those who gave offline exam
4. You have one more week of preparation time than students giving exam offline
Cons
1. If the system crashes you are in big trouble (which happens quite a lot)
2. The question paper will contain less mistakes so you won't be getting grace marks
3. You cannot cheat.
4. If you don't know how to operate computers you have to adjust which is hard
Offline mode
Pros
1. If you are old school (like me) you can give offline exams.
2. Offline exams give you one week more time to prepare for the main one "jee advance" and other competitive exams like vit exam
3. No system crashes, you have full 180 minutes and no one can take that from you
4. You can cheat if you are good at it.
5. For jee mains you have two choices but for advance you have to give in offline mode only. So, better be prepared for the jee advance but if you have to clear only mains and get good NITs then go for online.
Cons
1. You will be placed in tier 2/3 schools with not good facilities which may ruin your mood and which reflects on your paper(happend to me when I gave Jee Mains first timw in 2015) but that is not the case always
2. If you are brillient student there there will be someone who tries to see your answers and that bugs people.
3. Higher examination fee.
4. Bubble filling takes time which is not good.
I hope you understand that there is no best method for the exams you have to chose what is best for you.
Happy learning. Ciao