I think if we will base on traffic and the number of visitors, AltcoinsTalks.com is by far popular that of another forum like bitcointalk, here's why ...
bitcointalk Creation Date: 2011-06-24
Traffic Rank: [https://www.alexa.com/siteinfo/]
Global: 2,397
Rank in country/visitors
United States: 2,658/18.7%
Japan: 3,180/6.1%
Russia: 1,663/5.7%
India: 2,995/5.3%
China: 6,695/4.3%
altcoinstalks.com Creation Date: 2017-10-15
Traffic Rank: [https://www.alexa.com/siteinfo/altcoinstalks.com]
Global: 399,190
Rank in country/visitors
Nigeria: 33,868/11.4%
India: 215,879/10.2%
Vietnam: 38,399/9.5%
Pakistan: 61,937/5.3%
Russia: 336,089/4.9%