I don't have insider access to the top 50 teams, but the top 20 gallery is open content.
http://espn.go.com/nba/photos/galler...nba-teams-ever
20: 93 Bulls
19: 89 Pistons
18: 65 Celtics
17: 60 Celtics
16: 01 Lakers
15: 15 Warriors
14: 14 Spurs
13: 83 6ers
12: 72 Lakers
11: 97 Bulls
10: 92 Bulls
9: 64 Celtics
8: 61 Celtics
7: 85 Lakers
6: 91 Bulls
5: 71 Bucks
4: 67 6ers
3: 87 Lakers
2: 86 Celtics
1: 96 Bulls
I don't know how anyone can rank the 15 Warriors above the 01 Lakers. I don't know how anyone can rank those 60s Celtics that high, either.
Once again, the 96 Bulls got overrated, 92 Bulls got dissed, 05 Spurs and 04 Pistons got dissed as well, same with 83 6ers (sidenote, people just love to underrate anything Moses related). 85 Lakers got overrated as well.