For JoSAA counseling, you should upload the marksheet that reflects your highest marks, which is typically your improvement marksheet if you have appeared for improvement exams. This is because JoSAA will consider the highest marks obtained when calculating your eligibility and rank for seat allocation.

However, it's important to keep the following in mind:

1. Improvement Marksheet: If your improvement marksheet shows higher marks than your original marksheet, you should upload the improvement marksheet.

2. Original Marksheet:If your original marksheet shows higher marks in any subject where you did not take an improvement exam, you should upload the original marksheet for that subject.

3. Both Marksheet :If you're unsure which marksheet reflects your best scores across all subjects, you might consider uploading both. This way, JoSAA can clearly see your highest scores.