13xs 20"x13 prop 14xs 21"x14 prop(was my Choice)
I tried them both and found that the 13 that I had in a Spark Evo was better than a 14 xs to my flying style.
but lovely motors both , i had a 14 in a Arixtra and I think that was a better motor for that ( i flies slower than the Spark)
It was also then (some years ago) more options in light weight props for the 14XS.
good motors both.