I would suggest you both of Brand Name and site functionality as branding is so important these days due to search engines as for instance when u search gambling is faster to get "gambling.com" site rather than other non named such.
Same thing for functionality as the more you have the more appreciation and enthusiasm some new gambler will have to join your gambling site.
A popular name makes it easy for gamblers to search, something that will attract their eyes and it should be a good site because the first impression would last. That's why it's very important for a developer to ensure that their site will impress the gamblers once they visited the site because that will make them stay, with the huge amount of competition in the market, making a simple mistake might make the site left behind from the competition.