I'll do my quick opinion, no way the 2012 team beats the 1992 team. They'd make it competitive but 1992 would win in a series.
2008 would probably beat 1992 or at least take it to a game 7. That team was REALLY good and I think their speed and athleticism would've been too much. Not saying they'd for sure win but they are easily the most competitive. Ditto for 1996 if we don't want to put "chemistry" into the equation.
And now I go back to watching.
1992:
PG: Magic Johnson, John Stockton
SG: Michael Jordan, Clyde Drexler
SF: Scottie Pippen, Larry Bird, Chris Mullin
PF: Charles Barkley, Karl Malone, Christian Laettner
C: Patrick Ewing, David Robinson
1996:
PG: Gary Payton, John Stockton, Penny Hardaway
SG: Mitch Richmond, Reggie Miller
SF: Grant Hill, Scottie Pippen
PF: Charles Barkley, Karl Malone
C: Hakeem Olajuwon, Shaquille O'Neal, David Robinson
2008:
PG: Jason Kidd, Deron Williams, Chris Paul
SG: Dwyane Wade, Kobe Bryant, Michael Redd
SF: Lebron James, Carmelo Anthony, Tayshuan Prince
PF: Carlos Boozer, Chris Bosh
C: Dwight Howard