That is a very tough question. I could divide this into two categories:
1. The song I've heard from my personal music collection the most.
2. The song I've heard on the radio the most.
Figuring out the answer to either of those categories would be hard enough, but then figuring out the winner of the two winners would be really tough.
You know what? I'm gonna go with AC/DC - Back in Black for the most on the radio.
The most from my personal music collection... That's a little tougher. I've gone through many times where I'll obsessively listen to certain albums, then move on to obsessively listening to other albums, leaving those prior albums in the dust. When I was a kid and teen, I didn't by much music, so I was more likely to play the same CDs over and over and over. Since I've been in my early twenties, I have been buying far more music, so my listening is spread out to more albums, which results in me listening to particular albums obsessively less common. And the ones I listened to obsessively when I was younger mostly have been collecting dust for the past decade and a half.
Welp, I think figuring out the answer to my personal music collection is impossible, and I think I've probably heard Black in Black on the radio more times than I've played any one song from my personal music collection, so I guess Back in Black is the winner.