Preferring a phone over another is a personal taste, people would love to trade their M9 with Note 4/Edge and other the opposite.
I think the people who are used to HTC Sense will find a hard time to adapt to TW, this was my case when I passed from M8 to S6, when I saw an M9 in a shop 2 weeks later I said ''oh my! I did a mistake, I should go back to this lovely HTC world'' and I swapped my S6 to M9.
Don't get me wrong, the S6 was an amazing phone but its software TW is still miles behind Sense 7