The admin should strive or work to get both a brand name that has a recall or is very much familiar with gambling, everything starts with a name and they will build their trust rating around that domain name, if they got a good brand name then they are on a good start and they can work on building their functionalities, these two go together it's hard not to have one, but the casino can still build its reputation without a good brand name.
I don`t sure that the brand name must be much familiar with gambling. We see such sites every day and often they sounds the same. But you`re right that brand name can`t be just the common word. And it must be chosen before the start - it can be used in marketing campaigns. And the site functionality is the main thing what will help to attract new gamblers.
I would prefer "Site Functionality" since if the known gambling site is not functioning properly then it is really obvious that they are focusing on the marketing side, which it will affect the gameplay and security of each account of the player and I think that this is very alarming for me.
Advertising is good but they should focus on the functionality of the website and also how they can secure the profile information of the player since it will be at risk for hackers if it's easy to hack.