Really, Premium is the best option.
As to why? Well, for starters, if a person can afford to pay for the game, they might have a better background than a non-paying player. This would mean a nicer community in general. Really, as you said, if they can't pay for the game, they won't pay for your server.
Also, it's so easy to circumvent bans on a cracked server. People just change their address, and IPs can be changed too. If you go premium, you will find it much easier to manage rulebreakers.
Of course, the downside is that by changing your server you will lose every cracked account player on it. But it would be a change for the better.
