Frankly, I wouldn't rate Washington as a great President for precisely the same reason.
The union was fragile at the time, he has to be #1 for holding it all together and helping to ensure the constitutional form of the federal republic we have.
Fortunately you do not have to.
Washington's greatest gift was to establish the various precedents for those chosen as President of the United States, including and most importantly, the orderly and peaceful transfer of power to a political successor.
Remember that there were many, including his officers that urged him to take power in his own name, and others that offered him a crown.
For me and for always, he is "First in War, first in Peace and First in the hearts of his countrymen"
regards,