Following Dr. Sam Wang from the Princeton Electoral Consortium, I have ranked the different models using a Brier score. It seems like my scores came out slightly different from his, probably because of the data I was able to find, but the results seem consistent.
As input the numbers provided by the New York Times Senate Model Comparison. I have converted each of the totals provided by them to the probability of a Republican win. Therefore, if they predicted a Democratic win by 75%, the number was converted to a Republican win by 1D% resulting in a 25% chance of a Democratic win.
After calculating the Brier score for each of the models, here are the outcomes in order of best to worst (lower Brier score is better):
Place

Name

Brier
Score

#1

Daily
Kos

0.091

#2

Washington
Post

0.104

#3

PredictWise

0.125

#4

538

0.126

#5

HuffPo

0.139

#6

NYT

0.139

#7

SanityIID

0.161

#8

PEC

0.172

As you can see, all the various models did really well.
Links:
Princeton Electoral Consortium – http://election.princeton.edu/
Wikipedia: Brier Score – http://en.wikipedia.org/wiki/Brier_score
New York Times: 2014 Senate Model Comparison – http://www.nytimes.com/newsgraphics/2014/senatemodel/#comparisons