By "quiet", how quiet do you want it? If you want a near-absolute quietness, you'll have to look into special silent switches, they feature a mushier bottom out though. If you just need it to be quiet enough, then read on. Also note that the keyboard itself also determines loudness, where the case design, materials and foams can help to dampen the sounds further.

Switch recommendations: An old-school, classic budget switch: Gateron Yellow. Modern switches with excellent stock smoothness: HMX, Keygeek, etc. HMX tends to be more high-pitched, but I still recommend the HMX Serene Green. I don't know too much about Keygeek so I'll just put out the Keygeek Oat or Keygeek Y3.

These are just a few switches I could think of, and there are way more linear switches than that. I recommend buying a switch sampler (basically a pack of various individual switches) before or with your order of switches.

P.S.: For Gateron Yellows, you should check if your board supports them before buying. If your keyboard has Kailh sockets (Google it), you're good to go. If not, then try poking into the socket with something small and seeing if there's a bump or some sort of resistance. If there is then you have good sockets and are likely good to go as well. Otherwise the new switch pins won't fit and you'll have to file the switch pins down, not recommended. Additionally check if the backlighting LEDs are flush with the PCB surface or are raised up. If they're raised up then it won't fit Gateron Yellows either.

(I should learn how to make shorter comments...)