To me, it's a good song to me when any of the following happen...
...it has a good beat
...it has good musicality with real instruments
...the lyrics are authentic, original, and have a good message
...and I in particular like repetitive, catchy choruses
This gem by Gym Class Heroes has join a few songs in my book that hit all of the above. I think what makes it even more for me is the video. It's inspirational. It's masculine. It's powerful.
Here's to the the inner "Fighter" in all of us: