Class is nice and all. And really good in certain situations. A lot of them, actually. Being classy is usually better in the long run. But swag, depending on the situation, could be better. It would depend.
Those boys who keeping trying to have swagg won't try you right A boy who is classy will treat you like the lady you are.
Step outside the situation. Or yourself. Either one. Think. Boyfriend, classy. That's what most girls want. BUT personally, situation. Being classy when staring down the barrel of a gun isn't going to help you. Being classy when someone attacks you isn't going to help you too much, either. But swag isn't going to help you in a meeting, or with the boss, or anything like that. I only really use what you'd call "swag" when I'm being confronted or I'm extremely relaxed. Then, it's natural. That's how I was brought up, and it's my personality. I don't really think of it as swag, but it's definitely not classy, it's just me, so I guess it'd be considered swag.