Shark bite or replace leaky valve?

[six50joe]

In our new home, it looks like the shut off valve for one of the hose bibs outside is under the master bedroom sink on the 2nd floor, coming off the sink's cold water line.

When I tried opening it (it had been closed) it immediately began leaking at the valve. Closing it stopped the leaking. Obviously it's why the previous owner had left it closed.

Would it be I unadvisable to replace the valve with a shark bite (with valve) to fix this problem?

 

[plumberscott]

I would fix the problem with copper pipe and have some soilder a new valve on. I do use sharkbite fitting but only to cap a line of while working, or when testing.