MAUDLIN I think this is the best of the Spotlight alternatives.
Finally, my files seem to belong to me again - I can now find them all. I particularly like the detailed control it gives over searches: eg “find all files modified in the last 36 hours other than folders” or “find all files of type A, containing the word B, in folder C, modified before date D, other than those containing word E in the filename”. You can save complex searches and recall them with a keyboard shortcut. Its quite helpful to study the templates in the menubar (eg 'Long lost files'). It was only when I did this that I finally grasped how to set up a boolean "not" search.
(Version 1.2)