Rashi on Bereishis 24:39 says that
Abraham said to [Eliezer] “My son is blessed, and you are cursed [Eliezer was a descendant of Canaan who had been cursed by Noah], and an accursed one cannot unite with a blessed one.”
And Rashi on Bereishis 24:8 says that if Eliezer does not find a suitable match from Avraham's father's house then
take him a wife from the daughters of Aner, Eshkol, and Mamre
We know Aner, Eshkol and Mamre are canaanites from Bereishis 14:13 where it writes "Mamre the Amorite", and the Amorites come from Canaan as written in Bereishis 10:16
So since Aner, Eshkol and Mamre are also descendents from Canaan who was cursed, why did Avraham prefer their daughter's over Eliezer's?