I'm a Habs fan but I gotta say that new Leafs logo is gorgeous.
For me, a good logo has the following characteristics:
1) It is easy to glean the team name simply by looking at the logo
2) Colors of the logo allow it to pop against both the white and dark jerseys. Ie. don't have to change the colour of the logo.
3) I don't want to read the team name on the logo. Otherwise, it's not really a logo.
So, with that in mind:
Teams that change logo colors:
Toronto, Tampa Bay, St. Louis, Calgary, Vancouver - not a fan of changing logo colors. There should be enough of a mix of colors so that it stands out on both jerseys, like Detroit, who only have red and white, yet the logo has enough of a mix in the wing to not have to switch the colour
Teams with writing on the logo:
Washington, Edmonton, Florida, New York, Brooklyn