The Torah Anthology
"Literally, God said to Abraham, "Please take your son." He worded it as a request rather than as a demand.
Abraham's test can be likened to the following situation: A king had a brilliant general, who was undefeated in battle. When his enemies saw that they could not attain victory over him, they assembled a large army, which they were not sure the general could defeat. Seeing the huge army, the king told his general, "This will be your decisive battle. If you show any hesitation or fear, your reputation will be ruined. All your previous victories will have been in vain."
God then told Abraham, "Take your son."
"I have two sons" replied Abraham. "Which should I take?"
"Your only one"
"But they are both only sons. Each one is an only son to his mother."
"The one whom you love."
"Are there boundaries in a man's heart? A man loves all his children alike. How could I differentiate between them."
"Take Isaac!"

http://www.gotquestions.org/does-God-have-favorites.html
Whether or not God has favorites is a tricky question because it is based upon our human understanding of favoritism, which usually means unfair treatment of anyone who is not favored. To completely understand the answer, we have to start with the truth that God is always just. We know He loves everyone because every human being is created in His image. His judgment is always right. So if He favors someone, it is the only right thing to do.

When we think of favoritism, we imagine a place of higher status and less responsibility. But God’s favor often comes with added duties and more difficult challenges. That title is also used to refer to Israel. God chose prophets and kings for His own sovereign reasons. God chose Solomon from all of David’s sons to become the next king. He gifted him financially, in popularity, and in wisdom.

Toldot: All My Children
By: Rabbi Jay Kelman
Despite this love for each other they had differing preferences regarding their children. "And Yitzchak loved Eisav as game was in his mouth; and Rivka loved Yaakov" (25:28). Here too, opposites attract. Yitzchak saw in Eisav much that he "lacked"; aggressiveness, worldliness, and street smarts. Rivka was attracted to Yaakov, a "man of purity who dwelt in tents", something missing from her upbringing.
Yet Yitzchak and Rivka loved both of their children. Despite the fact that Yitzchak was tricked by Yaakov, we are told that "Yitzchak called Yaakov and blessed him" (28:1) before instructing him to go to his uncle's home in order to find a wife. The Seforno (25:28) actually claims that when the Torah tells us that Yitzchak loved Eisav it means he also loved Eisav; presumably, his natural love for Yaakov was so obvious it need not be stated.
Rivka, despite her role in usurping the blessing meant for Eisav, clearly cared deeply for both her children. She urged Yaakov to escape, not just to save his life, but to safeguard the life of Eisav as well; thus, she exclaims, “Why should I be bereaved of both of you on the same day?” (27:45). Rivka is described as "the mother of Yaakov and Eisav" (28:5), highlighting her concern for both of her children. She, along with Yitzchak, was greatly disturbed when Eisav married Canaanite wives, as she was apparently hoping that he too would remain within the Abrahamic tradition.