Catalyzes the final step in the synthesis of long-chain linear esters (waxes). Has activity with both saturated and monounsaturated acyl-CoA ranging from 14 to 24 carbons in length, but C20:1 acyl-CoA is the preferred substrate. a fatty acyl-CoA + a long chain fatty alcohol = a wax ester + CoA Belongs to the wax synthase family.