If you have duel citizenship in Panama and USA is it better to marry your Panamanian boyfriend as an American which takes more time or as a Panamanian which you want and can he get a green card?

If it is anything like Canada, simply marrying a Panamanian is not enough to get him a Green Card. Nor will it matter whether you show your Panamanian ID or your US ID for marriage purposes when it comes to the Green Card. Once you are married, then you can go through the process of requesting a Green Card for him. However, even though you are married, he can still be turned down. Make sure you have all of your paperwork in order. If you get denied once, you will have a higher chance of getting turned down again upon resubmitting an application.