I tried all of the free replacements and some were decent. Classic shell worked and was free but the indexing piece wasn't working for me (I didn't put a lot of time into trying to fix it).
I went with Start8 which was a paid package by Stardock (I paid $4.99 US). What I liked about it was it was polished and very customizable but also made it easy to get into metro apps and the new start screen if I need to for any reason. One of the small things I liked about it was it had a setting to put a start menu on each screen with multi monitors (and also you can pin both metro and desktop apps to it).