Seagate barracuda has better read speeds than the Caviar Blue. The write speeds are about equal on Barracuda and WD Blue
Write Speeds : WD Caviar Black > WD Caviar Blue ~ Seagate Barracuda (almost equal)
Read Speeds : WD Caviar Black > Seagate Barracuda > WD Caviar Blue
So, I would personally prefer the Seagate Barracuda more.