Can I back up to one drive

Photos, yes. But the resolution of Photos and videos may get compromised if you choose an unpaid version of Cloud Drives (Google Drive, OneDrive, DropBox, Flickr, box, AmazonDrive, Adobe Creative Cloud etc)

iCloud backup is far better than any other cloud drive backup for iOS devices because...

Other Cloud Drive Backup for iPhone/iPad may not support

• App Data.
• Device settings
• Home screen and app organization
• iMessage, text (SMS), and MMS messages
• Purchase history from Apple services, like your music, movies, TV shows, apps, and books3
• Ringtones
• Visual Voicemail password
• Apple Watch backups
• Photo and Video resolution

Many more...