* My suggestions:
1. Full fledged file manager, obviously.
2. More toggles in action centre. List could be horizontally scrollable.
3. Long press on toggles in action centre should open more settings. Just like it happens with Wi-Fi now.
4. Less cluttered Settings page. For example, settings related to display like glance, time out, brightness, wake up, etc could be list on one place.
5. Ability to sort out app list and also viewing options other than list.
6. Ability to dismiss the individual notifications of a particular app. As of now, if my WhatsApp shows 5 msgs, if I swipe right, it'll dismiss all the notifications.
7. Optional: Ability to reply from notification centre only.
8. Cut & Share option along with copy and paste in text editing.
9. Keyboard shortcuts, anyone? Like if I write WP, it should be able to transform it to Windows Phone.
10. When you select a text it IE, other than copy, there should be a search option, too. UC Browser provides this option.
11. Support for more codecs in default video player, anyone?