Hi,
If I am honest, none of us really have the right to be repairing the screens on iPhone 6, Apple do it at a really reasonable price, and that's for completely original screens, plus you get to keep the warranty getting it done with them.
There have been a lot of issues with iPhone 6 screens, as a lot have been falling out due to the fact the frame is extremely thin, and a lot use poor quality HMG (Hot Melt Glue) to stick the glass to the frames. Also, there are a lot of screens which are thicker and you can not only see the difference, but feel the difference as it doesn't sit flushly with the housing, and there is some major problems with the frame lifting up by the mute switch, which then shows the LCD light from the inside.
If anything though, always try to go original. :-)