Is a ducane central air unit a good product or should you stay away have never really heard of them?

they are the same unit as Goodman which claims to have more units on the ground than any other. My son installed a 3 1/2 ton Ducane on my house 2 winters ago and we turned off our oil furnace.Until last mo. our largest bill was 130.00 to heat and about 85.00 to cool.Am waiting for ser. man now as to a 180.00 heat bill last mo. Hope this helps a little. Jerry Suffolk Va.