Windows Backup requires Windows to be installed to restore from it, which obviously won't work if your C drive fails. It's fine for backing up files and user data on small systems, but I've found it takes excessively long (like several days) once you start getting into the hundreds of GB of data. I wouldn't bother with it.
There is no "best" as they all have advantages and drawbacks. The ones I tend to favor are Macrium Reflect and EaseUs ToDo. I used to use Paragon Backup a lot, but feel their interface wasn't as intuitive (scheduling was a PITA).
Cloning will make an exact copy of the drive - what you need to copy one boot drive to another. Imaging copies a drive or partition to a file. This is what you want if you're backing up to an external drive. Image the entire drive to a backup file(s) on your external drive.
The software will ask you if you want a bit-by-bit (or sector-by-sector) backup. This will take more space (since it will also backup the empty space), but can proceed faster (the software can just read everything off each track in sequence, instead of having to look up each individual file).
Most backup software includes differential and incremental backups, which will save space and reduce backup time.
■Differential starts with a complete backup (A) and each day it only backs up the difference from A. So Sunday you create backup A. Monday you create backup B which only includes files which have changed from A. Tuesday you create backup C which includes files which have changed from A. etc. until next Sunday when you create a new complete backup.
■Incremental starts with a complete backup (A) and each day only backs up the differences from the previous day's backup. So Sunday you create backup A. Monday you create backup B which only includes files which have changed from A. Tuesday you create backup C which includes files which which have changed from A and B. etc.
Differential takes more space but is safer (you only need A + your most recent day's backup to restore everything). \
Incremental takes less space and time, but is more risky (you need A + all intermediate backups to restore everything). I believe EaseUs ToDo is the only free one which includes incremental backups.
If you only have a single drive, then make a complete backup image of the drive. Then do daily backups of all the OS and user files (minus unneeded things like the pagefile). That way if the C: drive fails you can restore a bootable drive via the complete image, then restore the current OS state and data via the daily backups.
And don't forget to make the backup program's boot CD or USB. So you can restore even if the C: drive becomes unbootable.