From an engineering perspective, the difference between the 14 AWG Lowes and the 18 AWG Apature is going to very little. Any cable will present 3 electrical characteristics to the amp. These will be added in series with the electrical characteristics of the speakers. Those 3 characteristics are its resistance, capacitance and inductance. Please note, that we are not talking about the amount of each of these characteristics for each wire, just the difference between one wire and the other. Typically, both the inductance and capacitance are more functions of the cable geometry then anything else. If the geometry of the two cables are similar, likely the capacitance and inductance are similar. That is not to say equal. however over short runs, such as this (10'), similar will mean only small differences. Also, for 10', the resistance difference between the two cables is small, again because of the short distance.
I would expect that you would not hear the difference so use the one your significant other thinks looks better (or less objectionable) and put domestic tranquility over the last modicum of performance.
Just my advice from a married engineering perspective.
Shelly_D