there are certain alt coins that drop difficulty to ridiculous lvls at random intervals, you can try those out:
1.
http://www.coinwarz.com/cryptocurrency2. uncheck sha 256
3. check on Scrypt
3. key in your farm's combined khz
4. key in the Power and Power Cost
5. click on "Calculate Profitability"
See which alt coins gives you the best return rate and the best growth rate (look at their charts). You might want to consider the ease of exchange at cryptsy or btc-e or at other alt coins exchange.