You don’t get much easier than skirting boards tbh (apart from none as above). You can even buy them pre finished and if your walls are nice and straight you can just stick them on. I use Pink Grip which sticks like shit to a blanket. Think you can get composite skirting that clicks together nowadays as well, although I’ve never used it.
I dont tend to use pre finished my self as I think they always need something doing to them. Get a mitre saw for the corners.
In bathrooms I’ve used tiles for the upstand that match the floor, or have used some plastic trim, which I was unsure about about at first but actually gives a really clean look. Can’t remeber exactly what it was though…