I use lye, aka NaOH. For me, at this time, it's better. But there are tradeoffs.
KOH is more tolerant of having a little (emphasis on little) water contamination in your oilstock. I test every batch of wvo for water content and dry it if necessary, so that has no effect on me one way or the other.
Also, the glycerin byproduct produced with KOH is a liquid at room temperature. With NaOH, the byproduct can turn into a pretty solid gell at room temp. In a pipe or a pump, that's a clog. I avoid the clogging problem by using excess methanol, approx 24% by vol of wvo. That keeps the byproduct nice and liquid and I recover the excess anyway, so it doesn't really cost me anything.
NaOH is about a third to a half cheaper in most places, but methanol is by far the biggest expense, so no big deal either way.
Also, I make premium handmade facial soap as a little hobby/business, which also requires NaOH.
Alternatively, if you use KOH, the byproduct can be used in limited amounts as fertilizer for the potassium and organic content. NaOH is toxic to plants. So if you need biodiegradable herbicide, NaOH is the way to go!
Just a bit complicated.
Finest regards,
troy