I maintain that in most cases, the classiest way is a simple alphabetical list of people who contributed to the project, possibly broken out into two or three sections ("team members", "contributors", etc). That's essentially what Valve does, and it creates the fewest fights. Except, of course, that some people think they don't get enough credit that way and insist on being special listed.

At the end of the day, nobody has cared about your exact listing on a credits screen in decades. It's a largely self serving piece of the game.

One should be careful to disappoint as few of the readers of the credits list as possible. I really like something resembling industry standard to avoid confusion, misunderstanding, and offending any professionals unnecessarily. On the other hand, as mentioned here, getting too specific is asking for problems also because of the way that many positions having evolving, revolving, and sometimes dissolving roles.

Discussion in the group is usually in order for these kind of resolutions of credit questions in your mind.

Clinton

My solution would be to just list what is most important to you in the credits. In other words, what do you want to be known as one day? What is the sort of recognition you care about?

Every indie developer ultimately plays many roles. I do game design, web design, marketing, QA, business development, etc. But I ultimately only care about being recognized for making a good game. So my credit is simply Game Designer. I'm not saying you can't have more than one credit. I'm just saying pick the ones that matter to you most.