That is a really hard question. I like all of them equaly, but the most interesting race in my opinion would have to be the Elves. For they have the most history when it comes down to the first age. But they are not my favorite race personaly. I would have to say... Men.
I've changed my favorite race to men. I actually think that they are more interesting then the elves. This is mostly due to the gift of men. They are not bound by fate so they have many different moral dispositions. That makes their history very diverse and the elves have a very simple history compared to them.
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Sing my world into being, Ainur. The universe needs your power!
I agree that the race of men is very interesting. In fact I love how they are in-perfect. Not only is it easier to relate to them, but it is great to see the temptation that they fall to (more so then other races that is) and how they can over come it. If they do that is...