For phone photos, Google photos/Dropbox backups works just fine. For heavy duty files like RAW and big JPEGs, go for a reliable hard disk. To be doubly sure, make two backups on two separate hard disks. Someone told me "hard disk are like feathers", treat them with utmost care.
I have 3 different hard drives and 2 of them just for the travel photos and videos.
I don't have any online back as i don't trust that platform much. So always have offline backup at 2 different places.