I suggest for a great testers to make a reward system. Now the great tester has only one advantage: it is an opportunity to choose any of his devices for testing, if three great testers are not already registered in the cycle. You can take advantage of this advantage quite rarely. I propose to make a reward for great testers for the quality of reports. For example, if the quality of reports is more 80% then add to the total amount some amount per month. Ideal if there are four stages: > 80, > 85, > 90, > 95. This is more motivating testers to do quality reports.