Apple or Android? This is like a religion war. There is no right or wrong. My main advice is to remain consistent throughout your family if you wish to share payment methods, subscriptions and app purchases. This also applies to parental controls that are much easier to enforce if all the children are using the same type of device.
Otherwise keep in mind that you get what you pay for. In my view cheap Android phones aren’t worth it: apps will run slowly and the battery won’t last a full day on intensive usage. If there is one thing that you can be sure, it’s that the kids WILL use their phones intensively and WILL brutalize them. So it’s really worth spending extra to get a good quality phone that will last at least two years (three if you’re lucky).
Maintenance advice: Make sure that you phone is set to automatically receive updates and that backup to the cloud is active. This way you will have better protection against security breaches and can restore your phone from backup if you lose it.