I mean, I have almost never peed while standing, with the exception of waking up and having to pee while semi hard/hard (mostly when younger), as I need to be able to basically aim that thing downward and sitting wouldn't work well.
Meanwhile peeing while sitting means you don't have to touch your junk, and if you do have to poo anytime soon, sitting down on a toilet will generally get that done at the same time (but if you stand, you might not notice till an hour or so later).
Finally if you live with women (I was married most of my life) it just stops there from ever being an occasion where you leave the seat up in the first place (btw, you ALSO have to actually raise the freaking seat, which means touching it, to pee).
In pretty much every way I find it more sanitary to just sit and piss.