Depends on situation, if you are in open space, longer stick has better reach. BUT, if you are walking on streets with more people, in restaurant etc., longer stick can be liability. You cannot swing wide, you'll hit things not intended and you might lose your stick. The longer the stick, the harder it is for close quarter.My preference is making walking sticks. They are longer than canes and shorter than hiking sticks. I reference them as to walking support. I've had to use them more than once to deter an aggressive dog! The wife and I walk every day no matter the weather but I don't leave the house without my walking stick for defense if ever needed.
Also just as important. One need to practice hitting things, don't just carry it out. Don't think the stick is not that heavy, when swinging, it's a completely different thing. I am not that weak even compare to younger people. I do weight training, I still bicep curl with 40lbs dumbbell, 25 pushup wearing a 75lbs weight jacket with feet 2ft up on a chair. 18oz cain can get slow even swinging with two hands. So practice swinging and hitting something to make sure you can swing it easily and repeating hitting. Nothing is worst if the other person grab the stick and use it against you.
I practice almost 2 years since the news was talking about older Asians were being attacked on the street unprovoked during Covid.