Important site for formation of glycoproteins and glycolipids is

Proteins synthesised by the ribosomes on the endoplasmic reticulum pass into the Golgi apparatus through its cis face.
In the cisternae of the Golgi apparatus these proteins (and lipids) are modified by the addition of sugar residues (glycosylation) before being released from the trans face.
NCERT states that the Golgi apparatus is the important site of formation of glycoproteins and glycolipids.
Lysosomes contain hydrolytic enzymes for digestion, vacuoles store sap and waste, and plastids are concerned with photosynthesis and storage.
Hence the site is the Golgi apparatus.