Noctis:
Middling. He doesn’t really know how to give one, considering his own aversion to people touching his back, but he’d be willing to try. It would result in a massage that was basically pressing too hard in one place, and not hard enough in another. But hey, it’s the thought that counts.
Prompto:
He’d be a little too gentle, for fear of pressing too hard, but does make a decent effort. Unlike Noctis, his massage is going to be more even than anything, and though you’d still feel some strain on your back muscles, it’s considerably less.
Ignis:
He, surprisingly, doesn’t know how to give one. But having received them before, has a starting reference. And his eye for detail would be able to pick up what feels nice to you, or when he might be hurting you. All in all, you’d be super relaxed by the end of it.
Gladiolus:
He knows how to give a massage. A serious massage. He actually learned how so he could stop his own muscles from cramping, but now since you asked…He’d also probably be the best at it, and he’d be able to rub out tension in your muscles you didn’t even know you had. You’d probably be a puddle on the floor because of how relaxed you were by the end.
Imagine Final Fantasy 