Personally, I really wonder how the villains would of acted with each other.
Ras, never really got a chance to interact with Scarecrow.
Harvey dent and Joker interacted with each other, and I thought it was an amazing scene seeing the two.
Bane, and I guess Talia..but well, that was sold short I feel, so you could argue catwoman, which had a nice little scene or background knowledge with even catwoman scared of Bane.
But how Ras would have reacted around scarecrow, seeing bane react to Ras, or the Joker talking to either of those, they are all distinct characters in the way they act.
Overall, I feel Bane made a bigger impact than the Joker did on Gotham. Joker however made a bigger impact on Bruce, as Bane never really..."broke" the bat, but just the body, for a while.
Where as the Joker realllllly broke the Bat, what he set in motion, never really got fixed till 8 years later. And although Gotham was fixed, Bruce was so far gone, that suicide became an option.
To compare the two would be apples to oranges, I don't feel Joker was really ever interested in Gotham, but merely trying to ensure the world was just chaos, that you could reason chaos. That there was justification to chaos, that there really wasn't any other way to view things.
Bane had one viewing, that of the Ras Al Ghul and the league of shadows, it shows where loyalty can get you what path it can take you down, there's quite a bit of loyalty shown through out the movie, Bruce's loyalty to gotham.
Two opposites -
out of sheer preference I prefer the Joker...he really takes someone and makes them see things..differently, with reason. Chaotic reasoning, but it's well-reasoned, and yet bruce/batman does his best to counter that, and doesn't get swayed on his view point or lose sight of whats right or wrong, even at the worst of times. I think thats what I most enjoyed about the Joker, he has a way of swaying people, of manipulating or inspiring(whatever way you want to look at it.) them but in an evil way. Much like Batman tries too, but in a positive good way.
Bane on the other hand, is just pure evil, accepts that, and is much more like a dictatorship about it. It's my way, or I'll kill you sort of attitude.
Much simpler but simple doesn't always mean worse.