The best place to hunt dbs is the conquer website, if you use a super(+12) credit card you can get them easy
Anyway, I've had my joke now, I've found DBs all over the place no place is really better it just depends on where you hunt most and your luck. For example, people who say "I've found lots at BI" probably hunt mainly at BI, I've found them in lab, bi, ac, pc, az (ssm etc), pretty much everywhere (none in tc back when they could drop there and none from met zone either).