Wait for Face ID Improvements
It looks like Apple will make improvements to Face ID as well.
According to Weinbach, the company is preparing an upgraded system that lets you use wider angles when unlocking your phone.
Bloomberg's Mark Gurman and Debby Wu have released a report about the 2019 iPhones and they claim the new iPhones will have a brand new multi-angle Face ID sensor that can capture a wider field of view.
If true, this would let users unlock the device using Face ID when it's lying flat on a surface like a desk or a table.
That said, if you're unhappy with the current state of Face ID or simply want the best experience possible, think about waiting a few months.
iOS 13 will bring improvements to Face ID as well.