The best tactic in a good "buddy-cop" story - especially superhero buddy-cop stories - is having characters who are proper foils for one another (i.e., balance one another out).
Batman and Superman are more than characters - they are almost yin and yang archetypes that serve as metaphors for just about any conflicting philosophies you can think of (idealism vs. cynicism, brains vs. brawn, etc.). It's the same reason that Batman vs. The Joker or Superman vs. Lex Luthor tend to be the best rivalries: dynamic contrast. And, in the case of Batman and Superman, there are great rivalry AND friendship dynamics at work between these two titans of heroism.
It's not just the Superman/Batman dynamic that is golden: Bruce Wayne and Clark Kent work great together, as well. Bruce can literally buy and own The Daily Planet, while Clark (as an investigative reporter) can easily infiltrate the seedy underworld where Batman gets his hands dirty. The opportunities for farmboy vs. billionaire banter are limitless (both before and after alter-egos are exposed) and when you throw Lois Lane in the middle, you have the cherry to top it all off.