The best smartwatch for HTC One is Sony Smartwatch 2 right now (until there is a new one)...i've been using it, and it 's very useful and easy to use it...try it for right now....next time, u can try another one (the new one, just wait android wear from google i think)..
Sent from my HTC One using XDA Premium 4 mobile app
GT-I9000; I9000XXJVU;the latest nightly CM11
HTC Flyer P510e, DexterJB ver.1.8
HTC One M7u PN0711000