There’s no doubt about the fact that the true power of Android operating system comes from the freedom of being able to use various custom ROMs – firmware that have been cooked directly from the AOSP portal, or that differ from the stock ones in features, or those that incorporate elements from other devices. Not only does that bring diversity to your otherwise-boring smartphone or tablet, but also unleash its full capabilities for your usage. However, not all custom ROMs might sit well with your smartphone, and from time to time, there might be a need to go back to stock software to start afresh.
