The friendships between the major characters of The Fellowship of the Ring are adorably bromantic. And although the more emotion-allergic among us may blush a little at the soulful sentiment between Sam and Frodo or Merry and Pippin, it's this strong feeling of friendship that makes the Ring Quest possible. After all, at the end of Fellowship, Frodo doesn't take Aragorn (strong, brave) or Legolas (fast, also brave) with him. Instead, it's Sam who joins him. Sam insists on coming along because he loves Frodo, and Frodo allows him to come because he can't bear to go into Mordor without his dear friend by his side. It's the emotional bonds between these guys that give them the strength they need to resist Sauron. As in the Harry Potter stories, the only weapon Sauron doesn't have is love, which the Hobbits share in abundance.
Sam's single-minded devotion to Frodo is has nothing to do with friendship: as Frodo's servant, it is Sam's job to look after him.
Gandalf inspires more love than Frodo. The mourning that the Elves of Lothlórien offer for Gandalf after he has died demonstrates the sheer amount of love that he has inspired among diverse peoples.