I prefer the elder brother more, however, I think Alphonse is a good match with his brother. Edward is somewhat hot-headed and reckless, as the result he can easily be pulled toward dangerous situation. In that case there must be a person who can pull him out and protect him, as the family Alphonse totall fulfills that role. Alphonse is kinda a caring and protective character type, though his characteristics might be boring to many people, but when I see these two brothers as a whole, I see they are good match with each other and that makes the feeling of family connection and bonding between these two brothers touching.
Say... remember the time when the two brothers fight each other because Alphonse thinks that he is just an artificial robot, not a real human soul trapped in a metal armor? That reminds me, Alphonse can be easily fooled sometimes.