OOP, hands down. Though I never learned Functional (and never learned Smalltalk, for that matter. I think the OOP I learned wasn't half of what Smalltalk offer

OOP, hands down. Though I never learned Functional (and never learned Smalltalk, for that matter. I think the OOP I learned wasn't half of what Smalltalk offered.) I learned to program on punch cards, and the options were 'top down' ("The best way"), and bottom up ("The bad way"). Top down was hideous, because it ended up being decomposed as the next level as (1) Initialize things (2) Do what's needed. There was no clear path to subdividing the functionality. Bottom up was worse. Ya' know you're gonna need a routine to do such-and-such, so go ahead and write it. You get to feel productive. The huge down-side was that you couldn't figure out in advance precisely what was needed, so those routines always got re-written to be amenable to what was needed at a higher level once the higher levels were written. OOP gave me a way to think about the middle layers of a program in a way that isolated some element of what was needed and let me code it 'usably'. I could sit and think about an what kind of interface I wanted to provide, and get it right. It was also a big win to realize that even C (NOT C++) could be used in this paradigm, in terms of a boundary around the interior or some piece of functionality.