Neither. Don’t use chipped mulch OR shredded mulch. Both of those will rob the precious nitrogen from the ground that your plants need.
Nitrogen is vital for healthy plants because it’s a major component of chlorophyll. Chlorophyll is the compound by which plants convert sunlight into sugars from water and carbon dioxide. Nitrogen is also a major component of amino acids which are the building blocks of proteins.
Plants are unable to use or take nitrogen directly from the atmosphere. They must uptake it through nitrogen forms that include ammonium and nitrate.
So, what should you use instead of chipped or shredded mulch? Composted mulch!
This is from my Quora answer: https://www.quora.com/Which-is-better-for-plants-chipped-mulch-or-shredded-mulch/answer/Matt-Harvey-84