Well, i have had same bad luck once again and went through 2 replacements so far. The first 6s had the screen clicking problem, the second (TSMC) had a faulty home button, some spotlighting on the top of the screen and it got pretty hot during usage. These 2 6s have been exchanged through my carrier (T-Mobile Germany), they were factory new and i needed to wait on average 1-2 weeks to receive the replacement.
On friday, my third 6s arrived (Samsung). Everything except the screen is absolutely flawless - even the battery life seems to be fine (usage 8 hours, standby 41 hours in a bad reception area (1 to 2 bars) and im at 1% right now).
However, the screen uniformity is far from optimal. About 1/4 of the upper part of the display is noticeable darker than the rest. There is a fingerprint-sized darker spot on the upper left part as well. So, when for instance browsing macrumors with its white background it can be noticed - the middle is white, the upper part is a light grey in comparison.
I really dont want to go through another exchange through my carrier and wait for the replacement, as i sold my 5s last week. I guess, as i planned on buying apple care+ anyway, i m going to ask for an express exchange in a few weeks.