Do what feels best for
you. Most, but not everyone, are used to stick left buttons right. One example of a "not", if you're used to flightsticks, stick right, buttons (& throttle) left is the norm.
Story: I had a friend as a kid who loved arcades as much as I did (80's). He only played games with stick right, buttons left, which was fine as most stick games had buttons on both sides of the stick in the early to mid 80's. But as games started having more than 2 buttons and more than one player, they couldn't fit buttons on both sides. The standard started becoming stick left buttons right. And playing SF2 with arms crossed just wasn't cool. So he stopped going.
So if you like stick right, make your CP with stick right.
OTOH, if you make a 2 player CP and want to play others, you might want to think about having one player with stick right and the other with stick left; others here have done that.
OT:
I hated the NES pad the first time I saw and tried one, but it had nothing to do with which side the D-pad was on. I thought it looked stupid and it didn't feel right. . . . . And the NES pads worked great once you got used to them.
I liked the games, but never have grown to like gamepads. I'll use 'em if I have to, but give me a real stick any day. The only pluses I'll give gamepads are: they're cheap, they don't take up very much space, they don't need desk space to use, and they'll work for most types of games. But I'd prefer an arcade stick for arcade/platform games, a steering wheel for racing/driving, a flightstick for flying, or a mouse + keyboard for FPS & RTS. To me gamepads are like pocket knifes, has tools for every game, but sucks vs a real knife designed for the job.
But I know I'm a minority (hey, I think all gamepads are too small, except the original xbox controller).
