i found the stock htc one keyboard much improved in android 4.4, however, i have been testing swiftkey for the past week because of all the buzz and because i type in 3 different languages.
so far i have mixed feelings on it. the stock keyboard lacks all the fancy cloud features and the ability to "learn" from different sources but at the same time i found it to be less annoying compared to using swiftkey during the first week. in all its complexity, swiftkey assumes too much for my taste and so far it has been missing the mark too often - forcing me to review and correct way too many words. i am not ready to give up on it yet, but i am hoping it will improve considerably in the near future as i use it more.
perhaps i am not using it the correct way as well. it annoys me, for example, that every time i finish "swiping" a word it moves on to the next one without giving me a chance to select the other alternatives for that word - and many times the word it chose just makes no sense at all. also, and what is even more frustrating, is that it insists on using certain words that i have corrected time and again. the stock keyboard is perhaps "dumber" but at the same time appears to be more consistent.