1/2" pex.
I got this one for the toilet pipe. If you don't have the pex ring Crimp tool you can buy a push on Shark Bite valve.
SharkBite 1/2 Inch x 3/4 Inch MHT Crimp Angle Stop Valve, Quarter Turn, Brass Plumbing Fittings, PEX Pipe, PE-RT, 23064LF
https://a.co/d/dtGrk44