The HTC One M8 when released was one of the best phones you could get on the market, and according to the latest rumors HTC is certainly looking to repeat that. The HTC One M9 rumors if all come true would make the M9 one of the most desired Android phones.
5.2″ 2K screen with a 564ppi
Qualcomm snapdragon 805 SoC
64GB or 128GB versions
It is also safe to assume we will see a bigger battery maybe in the high 3000mAh range maybe even stretching the bar to somewhere in the 4000mAh range, and we should also see a better camera sensor. These are all just rumors for now and there is no definite release date but it is likely we will see this at Mobile World Congress in March of 2015.