Generally speaking, I have been quite happy using Nautilus with a little help from Tracker from time to time. Nautilus is a no nonsense file manager that allows most users to get the most out of their files and the way they choose to manage them.
Nemo is the latest effort to provide a new paradigm for file managers. Its approach, at least in its first early development release, is to combine file management with calendar views. Questions remain, however, about whether the concept will scale, and whether it is an improvement on traditional file managers, or simply different.