I would suggest you to go with the advanced version of apps, the cloud based app which could help keep track of the time in an hourly format and the lost of data which might be a risk in desktop appapp will be quite less.
But still if you are looking for some desktop app then rescuetime, timedoctor and replicon
- rescuetime
- timedoctor
- replicon
would be the best choice I would suggest you to go forgood choices.