Which one would represent complete combustion?

which one would make more sense for a complete combustion?

Neither, really. You can't verify whether a combustion is 'complete' or not, without stoichiometry.

But first we need to define 'complete'. In chemical terms this means that all the constituent chemical elements of the fuel have reached their highest possible oxidation state, post-combustion.

Take a generic fuel $text{C}_xtext{H}_y$ and its complete combustion reaction:

$$text{C}_xtext{H}_y+Big(x+frac{y}{4}Big)text{O}_2to xtext{CO}_2+frac{y}{2}text{H}_2text{O}$$

This stoichiometry tells you how many mol (or $mathrm{kg}$) of $text{O}_2$ is needed for each mol (or $mathrm{kg}$) of fuel, to reach the highest possible oxidation states ($+4$ for carbon, $+1$ for hydrogen, $-2$ for oxygen)

The presence of $text{CO}$ in the combustion products would mean the combustion is incomplete because the oxidation state of carbon in $text{CO}$ is only $+2$.