InShot is one of the most famous editing apps and is unanimously loved by influencers all around the world. It is probably the best all-rounder: you can edit videos and pictures as well as colour correct, add text, cool effects, filters, and change the size to suit the Stories platform, too. It's really simple to use, and free, with the option of in-app purchases.
Available on iOS and Android.
Image Source: Emma Frew