On the Bo or Kun
Or just plain staff, if you like. I've been working with it for some time, trying to add a long weapon to my repertoire.
It's a cliche that "every weapon has its own techniques", and that these techniques are dictated by the weapon itself: its balance, length, flexibility, etc. I found myself unimpressed with the staff at first. "I can't think of any situation where you wouldn't be better off just breaking it in two and have a pair of sticks," was one of my comments while practicing with a friend. I was, of course, used to arnis stick-fighting, which lead me to view every weapon through that lens. I though of the two ends of the staff as my two sticks, and was disappointed when I couldn't use them as quickly or simultaneously as I would my sticks. I saw a quality of the weapon as an inherent disadvantage, rather than simply viewing it as something to utilize.
The staff has its own strengths, different from those of the sticks. Its length is the most obvious: a lunge or strike can hit far further out (especially a sliding thrust, or nagashi-zuki) than the sticks can. But the staff has other, less obvious advantages, which I've only come to appreciate once I stopped comparing it to the sticks, and trying to use it that way.
The fact that one has two hands on the staff is a great advantage. With that leverage comes speed and power, especially if one remembers to use both sides of the body with every technique. It's particularly embarrassing how long it took me to realize this, when my bare-handed art stresses this double "aliveness" so strongly. If one hand is bringing the staff down on the opponent, the other can be either helping directly by adding its force to that vector, or indirectly by moving oppositely about a fulcrum between the load and the force, as a first class lever. The fulcrum can be any point on the staff two either side of which the hands move.
Moreover, the staff can be used at surprisingly close range, with both ends striking in quick sequence, or a double-handed strike (morote-uchi), which is a satisfyingly powerful manuever. It has a bare-handed counterpart in the double palm-heel strike, which can lift an opponent off their feet and leave them flat on their back (the secretis a slight upwards force-component). Of course, if your opponent gets two hands on your staff, as they might at close range, it's as much theirs as yours, but while they're trying to do that, one has any number of unpleasantnesses to visit upon them.
I love the thrusting techniques with the staff, too. A quick jab to the instep, ankle, or knee is enough to ruin anyone's day, and transforms into a sweeping upwards strike very quickly if it doesn't achieve its objective. Thrusts can come at odd angles and to unexpected targets, and have one's full weight behind them. The old quarter-staff fighters were renown for the "bursten bellies" they left behind--one can see, a little, how they did it.