I put this one on my 6s+ on Friday
http://www.amazon.com/Protector-Anti-scratch-Protectors-Bubble-free-Shockproof/dp/B00QZRYLBQ
can't beat it for $11. It adds a bit of thickness and you can feel it around the home button but that's the case for most glass protectors. Does not affect 3D touch at all. Best if you're also using a case because then you can't feel it on the sides or tell that it's on at all.
I was thinking about getting a Cinder because the glass is fully curved and may feel smoother on the home button but $30+ for a screen protector seems ridiculous.