This is the best app for creating custom stickers for WhatsApp.
You can create custom stickers using photos from your picture gallery. There is a lot of options to erase parts of your picture and create your perfect sticker.
Also you can write custom texts over on your stickers with multi color and there is a lot of font options and styles.
Additionally you can add a lot of existing emojis to your new sticker.
Emojis and photos can be customized with hue color and saturation changes.