I know the BBC did a version that is supposed to be very good. It's in our church library. I have never seen it, though.
I read the Narnia series when I was a teenager and liked them, but it just goes to show that I'm not a big fantasy reader. There were good but I had no desire to re-read them.
Tolkien is truly a big exception for me. I never get tired of reading The LOTR and can pick up a book and begin reading anywhere in it and enjoy it. No other fantasy story (or any other genre for that matter) appeals to me like LOTR.
I like Watership Down a lot, though.