Generally I use all the popular apps that everone uses such as google search, google maps, facebook, whatsapp, weather, stocks on a daily basis in iphone 6.
In addition to the above, I have the below few apps that are really helpful and makes my life easier. I use these apps also more frequently.
Google Drive: I store lot of documents in google drive. With the app, I can access the documents from anywhere and email to others as needed. Also I can upload the photos from my phone to google drive instantaneously and clean up the phone storage.
Bank App: Using my credit union bank app, I deposit check, set up bill payment, check account balances with just few clicks. With iphone 6 I login using the touch id.
CloudPlayer: Using this I play the music directly from Google Drive which saves lot of storage space in the phone. For offline playing also I can download and keep music locally. Switching to keep the files either in the phone or in the cloud can be done in 1 click. Very useful and haven't experienced much issues while playing the music directly from cloud.
CamScanner: Another fantastic app used by my entire family to scan documents using phone camera, convert them to pdf or txt file and send them via email/fax. Saves lot of time compare to using the conventional scanner. You can also upload the scanned document to the cloud - Google drive, dropbox, onedrive, etc...
Dictionary: This app helps to get the meaning of a word and pronunciation instantaneously. By following ‘word of the day’, lot of words and their pronunciation can be learned over a period that can improve your vocabulary significantly.
Great Clips: By signing in online for a haircut using the app, I always avoid long waiting when go for haircut. This saved lot of waiting time.