I find my motivation is the prizes (mainly points) and for inspiration. I often have a stale imagination so I need contest themes to help spark ideas. But I am not ashamed to say a large reason I enter these contests is because of the points. I simply don't have the extra money at this point in my life to purchase points or stock. I rely on these contests to purchase tutorials, stocks, and core membership.
Current community volunteers are listed here communityrelations.deviantart.… photomanip is Gejda - Marta should be able to point you towards more info as I am bound to have missed some! also check out Lora-Vysotskaya she has a great monthly update list of contests, and theres also an up to date list on her profile too
I like it when it involves collaboration Like our annual writer + illustration contest at CollaborativeMinds or the Tandem contest a while ago where I got the awesome experience to mix one of my watercolour textures with a macro picture (wuuuuut???)
And definitely using stock is something I love. I do use a lot of references for my sketches already. But a lot of the time the stock use challenges are only for photomanipulations and even though sometimes it's open to all media, the stock choices make it so it's difficult for me toproduce something. I see pegasuswarrior is also interested in drawing from stock, so yay i'm not alone ^^
oh and btw, I prefer small challenges to contests, because it's less stressful, and it's ok it you don't produce a masterpiece. plus the main goal is to have fun in community and improve our art by trying something new!
The theme and also the medium. I would want it to be open to traditional artists because I like to do traditional drawings. But I like it when other non traditional artists can enter. I like to draw from stock photos.