Board exams are just around the corner and till December most of the students are done with their syllabus so I am assuming you have also completed the same. So now, the time has started for revision and for that purpose sample and previous year papers are the best sources as these will be helping you to know all the important topics and questions so I would say better to complete last 10 years papers and once you are done with these,start doing topic and full length online mocks because these test are very important to get to know the actual exam pattern and time management skills but these test will only help you in a right direction when you take the test analysis report seriously so whenever you complete the test, check the report and mark the topic where you are making mistake then revise it again and go ahead for second test as this process should be continued.

Good Luck!!!