You might want to look at the studies and datasets done by Kenneth French. The main difference between his successul momentum and reversion factors is time.
Also, I remember reading on another site a post by an extremely succesful trader/developer well known to elitetraders that indicated that, for equity futures, his research suggested the following time frames had the following characteristics:
- ultrashort timeframe (seconds to a minute or two) - mean reverting - (think scalping or marketmaking)
- intraday (3 minute bars to 60 minute bars) - trend following (i.e. think ORB)
- Days to a weeks or two - Mean Reverting (i.e. - a really short period RSI system)
-weeks to months - trend following (i.e.- the Turtle Strategy).
Hope this helps. Just don't take this for truth, research it yourself.