You can be disgusted as you want but you need to take a step back.
a) I would have moved my bags which would have solved the problem
b) I would not have pulled out my sidearm because that was not a life or death situation
c) going from zero-to-firearm is a big leap which would exceed equal force and you should have other tools in your toolbox
You were on a bus full of young adults going to summer wrestling camp. He was a senior in high school. You are what I assume a junior or freshman. That is the data you have provided. You're seriously arguing that he was going to murder you on the bus full of your peers and witnesses? Obviously your hypothesis is incorrect because you're still around. If you happened to be 21, had a handgun, and killed him, you just earned yourself a trip to prison.
There are very specific circumstances that must be satisfied before you can use lethal force, and very specific training is required to recognize furtive movement and pre-assaultive behavior. Without those training tools, you
a) easily overstep legal bounds that qualify as self-defense because you have no idea where the boundaries are
b) have no idea how to tactically evaluate the situation and react appropriately
c) have no credibility or training to show in a court of law.
Bullies and criminals are selfish. It would behoove you to understand the bully/criminal mentality. They want something from you which is why they confront you with demands. If you don't give it to them, they'll take it. If this guy was going to choke you out regardless, he wouldn't have said anything to you to begin with and choked you out. He did it to satisfy his ego and show off to his friends by roughing you up because you refused to submit to his stupid demand. The simple thing to do was just move your bags even if you weren't morally obligated to.
Marc "Animal" MacYoung is a well known (or hated) self-defense instructor who has a fantastic blog on the criminal mindset and how to de-escalate lethal situations, and it applies to bullying. Really, I suggest you or anyone read it before you run around and carry some sort of weapon. Spend a couple evenings reading the writings to understand the beast you're going against. Defending yourself is pointless if you don't understand the foe. Most people don't recognize red flags or ways out and due to ego or adrenaline, subconsciously escalate the situations into something physical. You might be "new to the game" but the rules are already in place, whether you are familiar with them or not.
Start here, a guide to de-escalation:
http://www.nononsenseselfdefense.com/deescalation.htm
Best way to get attacked:
http://www.nononsenseselfdefense.com/get_attacked.htm
And to bring this back on topic, I prefer crenelations, but for the mundane practical purpose when I set it down on a table. In my opinion, they provide some benefit over a smooth bezel as a striking tool, but only if you know how to use it, like a kubotan. The Fenix LD20 is a long, slim unit that works perfectly but that doesn't fit your requirements since it's 2xAA. A benefit of a longer light is that you reduce your chances of injuring your hand/fist/fingers/knuckles when you make a fist around the light.