You could set up categories that you're most interested in investing in (curation wise), set up a competition (hype) and allocate a top 5 or top 10 for each category. Start by putting each winner (No.1) for each category on your voter. If they start to abuse this a post too much and the quality is lost of simply if it's no longer profitable for you, remove them and move down a tier (No.2's). It means you won't have to constantly do a competition to keep finding new winners (time consuming) but also you'll benefit from the hype of the competition and in theory have a better more profitable model for your curation rewards.