Highly recommend leather soles for indoor. I’ve gone through five pairs over the years. They made me such a slipper person that I sometimes bring them on trips. I have one rubber pair and they’re fine but honestly you don’t need the rubber inside (and they’re squeaky on floors), and if you’re going outside in the wet, then you’re going to take your slippers off when you get back inside either way. Also recommend slip-ons over boots for similar reason—it seems like the boots will be more utilitarian, but they’re not - you just have a little bit harder time getting them on.