One option, if you need storage space less than 15GB, switch to use Google Drive. Or, you may carefully group your files and put them in different cloud services like Dropbox, Box, or even iCloud, etc... if you do not mind all the troubles. A quick way to reduce your storage size, move all your pictures and videos to an external hard disk instead of putting them in OneDrive.
If you are thinking of buying a new phone, you may consider ASUS, which offers 100GB Google Drive space for about 2 years. I am sure you can find similar offers from other vendors, ...
ASUS - Redeem Google Drive Space 100GB:
If you are very concerned about what would happen to your files in OneDrive starting July, check this out:
Honestly, no free lunch. Yet, also time for us to rethink how we are using cloud services. At times, we have to admit that we have entered a kind of "lazy" mode and abusing others' "kindness"...