Under Sink Shut-off Valves

Hi,
When choosing a shut-off valve I see the outlet connection comes in either an 3/8" or 1/2" connection. How do I choose which one to get?. Is their any reason to choose one over the other?

depends on the faucet inlet size

We mostly use 3/8" compression stops on the outlet side.
My supplier doesn't stock 1/2" IP stops and a few 1/2 compression stops.

The sizes available include 3/8 and 1/2 flare, 3/8, 7/16, and 1/2 compression, and 7/16 + 1/2 slip joint=1/2 ips thread. Valves and supply lines are available in all of those. BUT....the trade has widely settled on 3/8 compression as the size of choice. Since the actual flex supply tubes are pretty much all the same ID, there is no practical reason to use a larger size fitting if you are starting all new.

Because of this de-facto standardization, there is the widest availability of valves, lines, accessories, adapters,etc. in 3/8 compression. Any other size, choices are limited and harder to find.

Thanks for the replies,

Sometimes it seem like when doing a simple project their are to many options available to accomplish the same thing.