While true, I can see Euryale and Stheno treating Ritsuka better than the rest. On account of her being rather cute, and being their master too but that's not as important as cuteness.
Another strong point is there are only two of them. They couldn't survive a millisecond if the made Ritsuka cry.
We got a counter guardian and a goddess for parents, the most well renowned king and a goddess of the underworld as aunts, two uncles who have trained under a god killer, a samurai who was able to perfect a technique that can hit three times in a single hit, the best kohai around, and many more.
And I'm sure we don't need to mention EMIYA's parents getting summoned and how Iri is gonna spoil Ritsuka rotten.