Many sites have attempt to copy btctalk and even pay their visitors to post there but no one succeed. They are still a plain forum with no signature campaign in the line.
Yes I saw also other forum like a local forum but I'm quite hesitant to join like I'm thinking that it's a scam and I'm just wasting my time there. I only trust this forum and it helps me a lot since then so I must say bitcointalk.org is the best among the rest.
For signature campaigns, I give it to this forum and it has really helped a whole lot of people which I believe I havent seen any other forum where anyone can earn huge compared to this one. However it has caused more harm than good as people are just fund of spamming and dropping nonconstructive just for the pay when information should be passed across instead.