According to Boyd's World conference ISR ratings, here are how the different NCAA baseball conferences rank.
Big West 109.7
Sun Belt 103.6
The complete list and other information can be found at Boyd's World. An excellent site for information about NCAA baseball.
It is a bit surprising to see the Big-12 ranked #1, and the Pac-10 #2. Normally the SEC and ACC have the top two spots. The Big-12 certainly is solid this year, with only Baylor and the Jayhawks having off years.