N8 is the better featurephone.
N900 is the better enthusiastphone.
N9 is the better smartphone.
808 is the better cameraphone.

Really depends on what features are important to you, or if you prefer an all-round better device.

For instance, the N9 is a "better" phone than the Lumia 800, but the Lumia 800 is all-round better smartphone because of its ecosystem (which isn't much).

Which is why the 2+ year old Samsung Galaxy S (EPIC 4G/i9000) is a much better smartphone than the Lumia 800, because it has much better software and also a much better ecosystem.