Does it matter how long you play college?

I was kind of speculating. My guess is that it really doesn't, since the talent level varies significantly, and people have different reasons for leaving or staying in school. Nonetheless, since I haven't done any of these speculations in a while, here we have it:

High School Only
PG	Monta Ellis	Louis Williams
SG	Kobe Bryant	Stephen Jackson
SF	LeBron James	Tracy McGrady	Rashard Lewis
PF	Kevin Garnett	Amar'e Stoudemire
C	Dwight Howard	Al Jefferson	Andrew Bynum
One and Done
PG	Derrick Rose	Jamal Crawford
SG	OJ Mayo	Corey Maggette
SF	Kevin Durant	Carmelo Anthony	Luol Deng
PF	Lamar Odom	Anthony Randolph	Zach Randolph
C	Chris Bosh	Spencer Hawes
Sophomore Sensation
PG	Chris Paul	Chauncey Billups	Gilbert Arenas
SG	Joe Johnson	Jason Richardson
SF	Caron Butler	Andre Iguodala	Rudy Gay
PF	Elton Brand	LaMarcus Aldridge
C	Rasheed Wallace	Brook Lopez
Juniors
PG	Deron Williams	Devin Harris
SG	Dwayne Wade	Ray Allen	Vince Carter
SF	Paul Pierce	Shawn Marion
PF	Carlos Boozer	Antawn Jamison
C	Marcus Camby	Emeka Okafor	Al Horford
College Graduates
PG	Jameer Nelson	Steve Nash	Jason Terry
SG	Brandon Roy	Danny Granger
SF	Tayshaun Prince	Shane Battier	Josh Howard
PF	Tim Duncan	David West
C	Brad Miller	Brendan Haywood
Foreign Club
PG	Tony Parker	Jose Calderon
SG	Manu Ginobili	Rudy Fernandez
SF	Hedo Turkoglu	Andrei Kirilenko
PF	Pau Gasol	Dirk Nowitzki	Nene Hilario
C	Yao Ming	Mehmet Okur	Marc Gasol

Now granted some of the one and done players might have tried to go into the NBA straight out of college (2006 and later) but for now, it seems we have a pretty good spread. What's your take? Juniors are pretty stacked.