Hello! Sorry for not seeing this earlier. The winners are chosen by me and @perceval. As we read through the posts we give each of them a rating based on how well they followed the contest rules, quality of the content etc. Choosing the winners based on likes is not a good system due to some users having a lot of auto votes following their account. It would not be fair to the newer and smaller accounts.
Thanks for bringing this up. We will make it clearer in the next one.
Thx for the answer. Good to know how it works. It would be nice to see in the further contests :D