I'd have to agree with Syd - most of us that draw on here can spot each others styles quite easily; I can tell Rach's and Em's usually, and Claudi's is very distinctive. My style's changed a bit over summer but I think it's still clearly "mine", so...
I think with art, though, it's hard to judge a "best" drawing - like you said, you'd have to have themes. I mean, if someone drew a still-life basket of flowers and another person drew a war-scene, someone into Warhammer would likely vote on the war scene rather than the flowers as that's what they like, even if the flowers were better... Nerf. I would participate but at the moment I can't get images online, so... Heh, I could draw them then submit them in september, when I get back online properly (back at uni)
