It all depends. While the ESV is considered "essentially literal" and the NIV a mediating, there are actually places where the NIV11 is more "literal" than the ESV. See Gal 1:15. On matters of translation, it really depends on a person's level of understanding in these matters. For example, if you're in a particular camp, you'll find the NIV appealing to you more. There tends to be some kind of "pressure." That being said, let's avoid confusing more formal and literal with accuracy. They are not one and the same. formal/literal does not equal accuracy. For example, while the NASB is more formal than the NIV, the NASB is not necessary more accurate than the NIV by virtue of being more formal.