I really prefer games without any kind of morality meters overall. Think including them just puts the designer in a spot where they come up with quest solutions that feel contrived or stupid because they have to support the good/evil mechanic, instead of developing quest solutions that are just interesting and logical.
I always loved the reputation system in the Fallouts. But it always irked me a lot that the Karma system is there in the background as well even though it plays a small part.
For games that actually embrace the good/evil thing, I'd have to say that Mask of the Betrayer is my favorite implementation for reasons outlined above. In most games, evil deeds often feel petty. And indeed, you're pretty much a dick in MotB as well but the combination of A) an "alien presence" inside you that's influencing you as well as B) there being a shot at incredible powers makes it all the more... well, believable is the wrong word, but worthwhile perhaps.
I don't know if it's true but it also feels like they had the two major story-paths in mind before they started working on the game. The evil path doesn't feel like a lesser version at all, or that it doesn't "fit in" or doesn't make sense. Instead, you really get to experience quite a lot of cool stuff that a good character would not.
I also hear Planescape:Torment had some pretty unique stuff for its evil path though I haven't tried it out personally.
But I mean, even in the case of MotB... The good/evil thing is obviously deeply imbedded in D&D but the game wouldn't suffer at all if they had done away with the system but kept the actions the same. There is IMO no real value in a gameworld judging your actions on a morality scale. I think it's better to just let the actions a player might take speak for themselves and have them carry consequences.
