On PC OneDrive is OK, only mildly irritates with premium promotions. On android phone it's OK, but irritates with premium promotions, notifications about synchronization and late file synchronization. On iOS all of the above + buggy interface + retarded UX decisions like "Help" menu on device shake.
GDrive is good on Android phone, but never used on other devices.
iCloud is OK on iOS and PC, but provides space for free and has somehow low synchronization speed.
At some point I, probably, will deploy my own NAS in the cloud.