Myself and a few of my friends have been using the very cheap ones from the Dollar Store. Yes, the Dollar Store. They have performed flawlessly. No scratches and the oleophobic coating is still doing its job. Another friend of mine bought the I phone 7, and had Verizon apply a tempered glass screen protector (she does not know the brand) and within a week of it going in and out of her purse, it cracked. She now has a cheap one installed and no issues.
I am not saying to avoid the more expensive versions. It's your money. But according to personal experience and that of many others, the cheaper ones perform every bit as well as the higher priced versions. At $1.00 each, I stocked up on them and give them to my friends. They all have positive experience with them.