Sounds like an app to USAA is a sure thing. I'd use that as a start point. It'll give you a rough idea of where the limits start, and once the first card hits a certain age, others will compete with limits/APR's
If he's interested in AMEX Green then that means he's willing to pay the card off in full each month. So, why should the APR matter?
Anyway, go with USAA since you have an account. Then in at least 6 months, try for another account. I think AMEX is great, especially for down the road with backdating.
Since he is a member, he should get a credit card through USAA. Since credit card companies like to see some history, he should hang onto it for 6 months before apping for anything else, then I say go for AMEX, Chase and Discover. Once he has had those for 6 months, he should be in really good shape credit-wise.
Like someone else mentioned, APR doesn't mean anything until you carry a balance and paying in full every month will take care of that.
Thanks everyone! I will let him know as soon as I see him at home! Yeah, I did ask him about the APR...and I told him also in our previous convo that as long as he PIF, that there's no reason for him to worry about the APR. He's good with his money, and we split everything 50/50, we do not have a lot of debt - so, financially we are good to go. But, he has expressed interest in improving his credit score, so, I'm doing what I can to help. He is an AU for my Discover and AMEX Delta CC.