When remodeling (or new), my preference is to use 1/4-turn, ball valves. On a conventional stop, the rubber washer can become hard and brittle so when you turn it off after not being touched for maybe decades, it can break apart, and never seal when you need it. A ball valve usually works more reliably. I probably wouldn't just decide to replace what was there unless I was swapping out say the faucet or changing the toilet, or, obviously, if I needed to do some repair, and the existing valve didn't shut off. It's much nicer to not have to turn the water to the house off when doing a repair, course, that main shutoff may no longer work, either!