new GPO, create an OU for it, or add individual users?

I want to push out an IM app and will have about a dozen or so people that want to use it.

So, more of a general 'best practice' question, but would it be better to create an OU in ADUC and assign the GPO to that, or just add the individual users to the GPO?

I have some thoughts about it in favor of both ways but I definitely would like to know what you have to say about it.

Thanks!