What do you think is better while advertising?
1) Making a fixed campaign with 0.2 per month for 5 best quality posters, min requirement only 20 posts , so something like 0.01 per post.
2) Advertising in bitcointalk with banner ads, with only one slot for 1btc per month.
IMO signatures are better because you get better visibility.
Signature campaign is a much better choice as it is more cost effective and can propagate to a larger audience. I do not agree with the idea of having 5 top quality posters at such a high pay rate. You can offer a smaller rate, example, 0.3 per month with 60 posts. It would reach a larger audience while being more cost effective. With this rate, you are almost guaranteed to get majority of the top posters. There is currently a filter which blocks the signature ad and people can also disable the option of seeing signature ads. However, those who are new/general public would not have ad filter and the signature can still be seen. Note that the signature would be changed in all the posts and thus your advertisement would reach people looking at old posts.