Which is the best choice to determinate qPCR amplification efficiency? cDNA, gDNA or plasmid serial dilutions?

Dear colleagues

I'm working with qPCR relative quantification and I need to determine the efficiency of qPCR amplification. I know we can use dilution series from gDNA, cDNA or template inside a plasmid, but what are the advantages and drawbacks of each one? what is the best choice?

I would really appreciate if you can guide me

Thanks in advance
My best regards