Who's data do you trust more Zillow or Trulia

[Gene Hacker]

I know Trulia is owned by Zillow but I find it interesting how the sales data they post are different from each other.

Examples:

Bakersfield CA Median home sale price change year over year:

Trulia: -2%

Zillow: +6%

Bakersfield CA Average price per foot:

Trulia: $136

Zillow: $141

Has anyone found something similar in their area?  Any insight into which of these two options to trust more?