[doug*platypus]

From reading Letters, I recall that Tolkien wrote to someone that he was most like Faramir. I can't recall which Letter it was, though. But my own opinion is that an author is necessarily like all of their characters. In order to understand, create and write a character, they have to have that in them to start with.

Of course, an author is more like some characters than others. To work out which, we can either look to Tolkien's life and what we know of it, or we can look to the characters themselves. Those that aren't fleshed out enough or feel significantly real would, imho, be the ones Tolkien is least similar to. And conversely, we may guess that the most fully formed characters (such as Gandalf, Frodo, Aragorn to name a few) are ones that he was more similar to.