I used this one on my M8 and currently have the M9 version respectively. Hopefully they'll be back in stock soon.

Mr Shield All New HTC One M8 2014 NEW Anti-glare Screen Protector [3-PACK] with Lifetime Replacement Warranty https://www.amazon.com/dp/B00IJT0CUM/ref=cm_sw_r_awd_wpqsvb1WRR02S