What an interesting post. I also like the omniscient narrator; it's hard to imagine Mansfield Park, say, being written by Henry Crawford. (One of your friends will probably now tackle this :-))I'm not so keen on the 'let the reader decide' attitude.
One of my favourite narrators is the unnamed 'I' in E Nesbit's The Story of the Treasure Seekers because it's a joke. I also love David Copperfield.