If you are using a long hose, 1/2" will reduce pressure/volume losses, but you will want a 3/8 whip at the end so you are not fighting the stiffer 1/2 hose.
The more important thing is to spend a few extra dollars and get one made from rubber. The PVC hoses never want to unroll completely, or roll up completely. They are a big PITA.
Rubber hoses are so much nicer to deal with. This is a good example.: