I think it would be best to move away from a duality system. Life isn't black and white, so this overly simplified system has no place in games that strive for realistic depictions of people. While ME is soft sci-fi/fantasy, the people in it are more or less realistic personalities with complex emotions, motivations and circumstances.
I don't really want an approval system either, because most of the time that's just making things unnecessarily difficult. Like preventing you from taking a choice because someone in your squad would disapprove and you want to start their sidequest which only triggers at 75%+ approval rating...
One of the worst examples for that was Bao-Dur from KotOR2, who needed to be in the party at specific times and places to gain approval with him - otherwise he wouldn't become a Jedi.
The approval system in DA2 pretty much solved that problem by introducing rivalry, that way your character could act like you wanted and your companions were still loyal, even if they disagreed with you.
I also quite like the reputation system of Pillars of Eternity, which adds points to certain characteristics depending on your choices.
Aggressive – Hot-headed, bold, or impatient. Some characters will think that you provoke fights and make only trouble, but others will admire you for taking charge, being decisive, and not letting people push you around.
Benevolent – Charitable, kind, soft, or weak. May be viewed as charitable and kind but others may consider the player weak or assume he or she will do things for free.
Clever – Sarcastic, sassy, foppish, or irreverent. May be well received by some as amusing, but other characters will assume that you are not to be taken seriously.
Cruel – merciless, sadistic, brutal, or imperious. It doesn't typically earn you a lot of friends, but there are people who respect (and/or fear) brutality.
Deceptive – dishonest, manipulative, or shrewd.
Diplomatic – Cautious, tame, or courteous. For example gained by remaining silent when two people are arguing and you choose to not interject.
Honest – guileless, sincere, or straightforward. Gained for being straightforward. e.g. telling a guard that you broke in the house.
Passionate – zealous, romantic, or obsessive.
Rational – practical, standoffish, or cold.
Stoic – tight-lipped, cool-headed, or simple-minded. Gained for being unmoved/quiet in dialog options.
http://pillarsofeter...com/Disposition
This allows you to act with more precision than simply being Paragon or Renegade. Combine this with the rivalry system from DA2 for the companions and you'd have a winning strategy.