Well, well! The few--the proud--the Silmarillion lovers! I adore the vast scope of its mythology and Tolkien's insight into character and motivations, and especially the great Creation story of the Ainulindale. It rings true.
As for favorites among LOTR, I feel you really can't consider them separately at all. Tolkien first intended to have the entire tale published in one volume--prohibitively extravagant in the 1950s, but not so now that we are accustomed to 900+-page fantasies. Indeed, I have seen one-volume printings of LOTR. It is so seamlessly interwoven you have to treat it as a single tale.
I also have a volume published during Tolkien's lifetime called The Tolkien Reader, including, among other things, the story "Leaf by Niggle" and a narrative poem, "The Adventures of Tom Bombadil." It varies in quality; the Tom Bombadil poem is lots of fun but that's all, yet Leaf by Niggle is deep and deeply moving.
I've hesitated to read the Lost Tales etc. simply because I know Tolkien would have liked to spend more time niggling over wording as he did on LOTR to make them perfect in every detail as LOTR is. On the other hand, maybe he would have liked the materials to be read in any form...