Formal:
* Maraming salamat po, mga mahal kong kaibigan. (This is the most formal and respectful way to say it.)
Informal:
* Salamat, mga kaibigan ko. (This is a more casual way to express gratitude.)
* Salamat, mga mahal kong kaibigan. (This is a slightly more affectionate way to say it.)
Even more affectionate:
* Salamat, mga kaibigan kong mahal na mahal ko. (This translates to "Thank you, my dear friends whom I love so much.")
You can choose the phrase that best fits your relationship with your friends and the situation.