I'd be interested to see how you would contrast Savage Worlds with True20. I like Savage Worlds alot but I also like open licensing alot.
I initially began as a developer for Savage Worlds and noticed some analogs between it and M&M. When True20 came out, there were further analogs that intrigued me and got me even more interested in the system from a developmental angle.
I'll address some of the more pronounced similarities first:
1. A wound system that replaced the artifice of hit points.
2. A corrolary to the above is that the wounds actually impacted your character's performance.
3. Both allowed characters an ability to manipulate dice rolls that heralds back to WFRP first edition's Fate Points (i.e. Conviction points in True20 and bennies in Savage Worlds.)
4. Both allowed the character to earn more of these points during play as a reward for good play.
5. Both more or less dispensed with experience points writ large. True20 leaves the onus on the GM to determine when characters level up, while SW has a simple experience point system that more or less does the same.
Now to get into a few particulars where they depart.
Savage Worlds is a classless system wherein you can select from a broad array of edges to define your character. In True20, you have three broad categories of roles: adept, expert, and warrior and you get a certain number of skill points to distribute among skills and a certain number of feats (likened to edges) that particularize your role from someone else's. Additionally, as each race in Savage Worlds has its own specific hindrances and edges, so too are the races in True20 defined with their own specific feats. True20 also has a category of favored feats wherein a character of a certain race, dwarf for example, might always be able to take stonework as a feat, regardless of their class. Feats, you see, in True20 are more role regulated. However, they also have no real penalty for crossing from one role into another. Some may argue that you have differing bonuses from one class to another, but that's best left to a seperate discussion.
Now, on to combat. Both systems use their opponent's defense as a Parry or DC. In SW, you must roll equal to or higher than your opponent's Parry to hit them, exceeding the number by four results in what is tantamount to a critical. Now, you have a Critical Threshold in True20 akin to that in OGL, generally a 20, but certain feats and weapons can expand that outward. When you hit someone in SW, you roll damage against an opponent's toughness to determine the result. In True20, whomever is struck makes a Toughness roll to determine the amount of damage they receive. In both systems, the person being hit may spend a point of Conviction/benny to attempt a better result and incur less damage.
The magic system in SW is based off of spending an edge to get an Arcane Background and that, in turn, gives you a pool of power points and a set number of powers depending on the source of the Arcane Power. Additional power points and powers may be gained by selecting them with various edges as you progress. True20, on the other hand, uses a more flexible system of magic wherein powers are selected with Feats but there is no power pool. You can strengthen or weaken your power effect and that determines the chance of suffering fatigue from using the power. Additional powers may be gained with additional feats and the governing attribute of various effects is determined by the character's type of powers, but chiefly breaks down into Int for magic, Cha for psionics/mentalist, and Wis for miracles.
Attributes in SW are die based from d4 to d12 and True20 runs the gamut of -5 to +5. In True20, you simply add your attribute and your skill rank to the roll of a d20 versus the DC of the task, which can vary greatly. In SW, the TN of most everything is 4, but penalities can apply to the roll for various conditions.
Both systems have mooks, weaker opponents that are easily taken out by the characters, usually with one hit. They also have the traditional more powerful foes.
Both systems are very strong and don't so much have weaknesses, but may, rather, cater slightly to different playing styles. True20 is more front-loaded and may take a bit more time to create a character the first time through, but honestly, in either it or SW, character creation shoudn't take more than fifteen minutes once you're comfortable with the system.
Personally, I've found people quicker to understand True20 than SW as they only have to focus on one die, a d20, and then add whatever their requisite skill/attribute to a die roll to go against a specific number. Distilling it down to its essence, it's that easy. It's amazing to see a group sit around and all there are about 4-6 d20's on the table. Scary in a way.
Savage Worlds, however, requires a bit more time for the new gamer as there are a lot of different dice being thrown around, but experienced gamers take to it almost instantly and are surprised at the freedoms in it.
A few closing comments: True20 is a huge step away from d20. It's very sleek and streamlined and a credit to its designer. It does have an array of options and is better able to handle finer details, if that's the groups desire. With those rules, does come a bit of knowledge overhead for a GM and creating NPCs and adversaries is more labor-intensive than with Savage Worlds.
Savage Worlds, on the other hand, is innately geared towards pulp or cinematic play. I only mean that in the finest sense. Each setting book that comes out for it tweaks the system accordingly, so the game can be played in a style best suited to it. Its biggest strength is the ability to quickly detail out NPC's and adversaries and to run larger scale conflicts with ease.
Honestly, both systems are excellent and I'm proud to be affiliated with both companies. I hope this gives you a good contrast of True20 and Savage Worlds and I'm happy to entertain any further questions or expand on any particular points as I am able.