This is a wonderful book that I loved as a kid and one that my son loved when we read it to him. If you haven't read it, read it! Now! Seriously!
Jane Eyre remains one of my all time favorite books and, like Jane Austen's Pride & Prejudice, I have read it numerous times. (I know that Pride & Prejudice's protagonists are not orphans but I just had to mention it anyway because it's one of my all time favorite books).
There are so many orphans in Dickens, but my favorite, like Charles Dickens', remains David Coppperfield.
Runners up would be Pip in Great Expectations and, of course, the obvious, Oliver Twist. "Please sir, may I have some more?"