Hope my experience of Apple cases can help you make that decision easierThank you all for sharing your experiences. My brother's 6S leather case hasn't stood the test of time well but I'm not sure whether that's just carelessness on his part or a genuine design flaw.
Not an easy decision :/
I bought a midnight blue case in 2014 when the 6 Plus came out and I've been using it non stop for two years. It hasn't worn as badly as you expect; apart from a couple of marks, it has barely discoloured. Were as my sister bought the red one and I kid you not after 3 months it discoloured so badly it turned black and orange! The leather cases have a really nice premium feel to it but as mentioned above, definitely pick a dark colour such as black or dark blue!
The silicone ones do feel nice in the hand, I used one for 2 weeks when I got the 6S Plus but quality issues had led me to return it (a white pocket of air had bubbled up and began peeling near the camera and the inside fabric began to split from the case). I couldn't be bothered to get another one and just returned it and stuck with the leather one. I'm sure the quality of my case was a one off as many of my friends and family are still rocking theirs!
Hope this helps, I can send you a picture of my case, so you can get an idea of how 2 years of use looks on a leather case!