are we talking about this era or in history.

I mean Nintendo's big one would have to be their role in transforming Sony into a direct competitor in the Video game market

Microsoft best:
XBL
One-year head start*
Microsoft worst:
RROD and other problems caused by rushed design*
Charging for XBL
HDD not standard
Super-expensive HDD ($100 for 20GB?  Go to hell MS)

*The good and bad are intertwined but I count them separately

Nintendo best:
$250
Wiimote
Wii Sports pack-in
The big guns -- Mario, etc.
Nintendo worst:
Not enough production increase
Friend codes and generally being slow to embrace online elements

Sony best:
Upgradable standard HDD
PSN is free
Blu-ray*
Sony worst:
599 US dollars
Their marketing/PR in general
Getting rid of BC
SKUs coming out like crazy
Blu-ray*
Losing exclusives

*Having Blu-ray in the PS3 benefits the company as a whole much more than it does the PS3 but I think it was still sound strategy on the company's part, and there are / will be benefits to Blu-ray for the PS3. 

Microsoft Best:
+one year head start
+bought/sponsor 3rd party exclusives

Microsoft Worse:
-bad hardware design - RROD
-too focus on FPS, and eventually labelled as "FPS only" console


Nintendo Best:
+innovation: Wii motion controller and IR pointer, DS touchscreen
+bring in new audience by introducing casual games genre, family oriented games, party games
+mainstream pricing of consoles
+lower development cost for developers

Nintendo Worse:
-not enough disc space for VC/WiiWare/other downloads
-lack of good quality 3rd party support
-underestimate demand, lost sales

Sony Best:
+introduce 40Gb PS3 in time to gain back market shares
+bring back rumble to PS3

Sony Worst:
-no killer games at launch (should have move GoW2/FF12 to PS3)
-many poor hardware decision (controller without rumble, powerful processor but difficult to write codes, bluray increases PS3 cost)
-marketed as converged devices, and gaming become secondary. this leads to bad software sales in PSP.

Sony:

Good:
Making a really high end unit instead of a PS2.5
Waiting to release the system a year after MS rather than rush it out the door, ASAP
Creating the 40gb and selling it at a minimal loss.

Bad:
Launching with such high prices.
Launching with a pathetic library and little to back it up for nearly a year.
Continually releasing new SKUs.

Nintendo:

Good:
Launching with a reasonably priced system.
Making the system innovative.
Launching with quality games and having quality additions to the Wii library over the first year.

Bad:
Making a system that graphically isn't much better than last gen.
Under production of Wiis
Haven't produced enough titles like Wii Play and Wii Sports and have instead fallen back on Mario, Zelda and Metriod to push the system.

Microsoft:

Good:
Launched first
Has managed to pick up 3rd party support.
Has managed to make xbox live a strong selling point.

Bad:
Rushed the system out, resulting in very high failure rates.
Has had numerous problems with Live, continues to try and nickel and dime customers to death with xbox live and by making nearly all the content cost points.
Tried to push the system in Japan.

I pretty much agreed with all that Renar said.