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.
You are not getting a banner ad slot for 1 BTC a month. Try 10 BTC and you may have a chance.
Currently the ad slots go for over 2 BTC and was mnore than 3 BTC for the last round, and they are for 7-12 days. So in a month it will cost you over 10 BTC and for that budget you will have a huge signature campaign. If you have only 1 BTC a month to spend then you dont have any choice other than a signature campaign.
Out of interest, what is your site?
EDIT: I see that youre doing this out of academic interest. But your numbers are still wrong.
Yeah this sounds right, if you have the budget OP then go for the banner ad as I think it is more visible as it hangs on top of every thread on the whole forum but if you don't have a budget then go for signature campaign but only 5 members is very less, atleast make it 20 members if you want your site to exposed to a wider audience.