Metabolically the most active of the plasma lipids is
Free fatty acids 

Plasma lipids consist of triacylglycerols (16%), phospholipids (30%), cholesterol (14%) and cholesteryl esters (36%), and a much smaller fraction of unesterified long chain fatty acids (4%). This latter fraction, the free fatty acids (FAA), is metabolically the most active of the plasma lipids.
Phospholipids
Cholesterol
Triacylglycerol
Free fatty acids