FWIW, here are the teams who I think have better defense than the Lakers:
Minnesota (#1 defense in the league IMO)
Cleveland (but only as long as G-Wall is a fixture in their rotation; otherwise we're about even)
Oklahoma City
Milwaukee
Washington has a case because of their very solid starting lineup, but their bench is completely devoid of defense.
I do have a feeling I missed a team...
TP to someone for recognizing just how good the Bucks can be on defense.
I have two elite defenders at rather important positions (PG/SF), and another very solid defender at C. My 6th man (Ariza) is also a very good wing defender. PF is somewhat of a weakness on D, but Reggie Evans can fill in when stops are needed. He's not sexy, or elite, but physical and competent. Evans also rebounds like nobodies business, minute for minute there really aren't any better rebounders.
Conley, Ariza, George, Evans and Okafor would make a nasty defensive lineup (while somewhat deficient on offense). Obviously that is a situational lineup lineup, but still very good for end of game situations, where Conley and George are both good in the clutch, and Ariza is a threat from 3pt range.