How may apps are there in your phone? Without considering them as battery killers, you can add the following 5 apps.
Internet Speed Meter – Internet Speed Meter Lite – Android Apps on Google Play

Living in India where internet speed and network are so unreliable it gets you paranoid when stuff you open doesn’t really open. So if we keep monitoring our network speeds via Internet speed meter then it becomes quite a relief.
Flesky – Fleksy + GIF Keyboard – Android Apps on Google Play

First thing I need in my phone is a good keyboard and trust me I have tried them all, (the bests) Swifkey, Google keyboard, Swype etc but nothing is as close to my heart as Flesky. Its key placement is just right and you will never hit the wrong note, you should definitely give it a try.
App Dialer Pro – AppDialer Pro T9 finder – Android Apps on Google Play

How many apps does a normal user install? 50? But for me it can even cross 200 and with so much of them it is almost impossible to find them quickly if you don’t have the proper tools. App dialer pro is just the one you need in this crisis, it has t9 search which is super-fast and easy. Give it a try.
QualityTime – QualityTime – My Digital Diet – Android Apps on Google Play

With infinite possibilities on android you will never get bored and end up wasting a lot of your precious time (and may even procrastinate). For people who fall in this domain we need something to monitor and break away this bad habit and luckily Quality Time comes to the rescue. It can monitor your usage and even block apps usage if you want.
HabitBull – HabitBull – Habit Tracker – Android Apps on Google Play

Power of habits can make you do things you never dreamed off. I have used many goal trackers but finally settled for this feature rich app to track my day’s productivity.