Alot of times, many android users download alot of third party apps when they are not really needed and begin to run out of space just immediately. If you don't like the stock app your phone came with, it's probably because they are old, ugly and non productive. Most low and medium class Android phones (which is the most we use in Nigeria) comes with outdated stock google apps. And by downloading an alternative, you are using up space. Instead just update the app and get as much productivity that you will get from any other app. Example is the "google play music" now adays most people use TTPod but after updating my play music, I uninstalled TTpod cos there is noting TTpod does that play music does not do if not better. Plus you know Google stock apps can't be uninstalled unless you root ur device. So u save memory embracing them. You should also know Google don't make sub-standard apps. By the way, play store might not show updates for stock apps. You will have to search them out yourself and update. Other apps are; Google keyboard, Google calendar, messenger and others.
However, if you have enough space, or you feel there is just something the stock apps are missing, you are free to install the world.

Source: self

But you didn't really tell us how we are going to update the stock apps