In my opinion, the answers you will receive to such a particular question “your best jazz song” might not help much, it would be a bit like asking the world population in all cultures and age groups what their favourite meal is. I don’t have one song for you unfortunately.
What I sometimes get as a somewhat similar question: how to learn to actively listen to and enjoy jazz. There likely are many ways to approach this, listen a lot would be one of them. That alone might not be enough for you, I don’t know.
What might help is not to focus on the songs, but on the individual musicians within the songs and in what year it was produced. Some (unfortunately a lot not) have made music for quite some years. If you learn how to recognize these musicians and how they handle their instruments, you will be able to understand their progression and how Jazz progressed and went in different directions. You might then learn when certain musicians delivered music styles you liked and when they didn’t for you. I for instance, love mostly all Herbie before '81, after that, not all so much. Then, combining these musicians in different group performances is equally as interesting.
To make an example out of this (but choose any musician that got your attention or plays the instrument you favour most):
Herbie Hancock, Jack DeJohnette, Ron Carter, Miles Davis (you already have a box set) to name a very few with different instruments, have been around for so long, produced and some still do so much, have worked in so many combinations with so many other great musicians in so many different styles of jazz, emphasizing on either one of them would greatly benefit your ability to actively enjoy jazz music and develop your own preference. Start for instance with only Herbie, learn to recognize his chords and timing, and notice how he changed jazz styles from his 60’s recordings up to late and you are set for months and months of learning. During that, read up on what you are actively listening to, who are also playing in the set and in what manner and before you know it, you have unconstiously developed preferences for certain bass players, horn players, electric bass/piano vs acoustic etc.