The best backup is a backup that works great for you. The top two that I'd recommend that has already been mentioned is Aomei free/pro or Macrium free/pro. Great choices as mentioned by
@Garzaman !
I have been using Acronis True Image for a long time. Sometimes you can get it for free on Newegg through a special. I got the 2017 version a while back and upgraded it to the 2018 version for free (free of any and all costs).
The only thing I hate about EaseUS Todo Backup and the reason I stopped using it, is that the backup notifications (which I didn't find a way to disable) minimizes fullscreen windows, for example games. That is unacceptable for a gamer
EaseUS Todo Backup is ok....However, I have heard far too many sad stories of stuff getting lost in this program due to random things happening. With this being said, I wouldn't recommend this software to anyone at the present time.
Top choices:
Aomei Free
Macrium Free
Aomei Pro (I'd go for the lifetime myself for the extra $10 dollars or so)
Macrium Pro
Acronis True Image Free for Seagate and Western Digital Users
Acronis True Image 2017 & 2018
I would always keep a full backup on hand - meaning a full disk image. Personally, I would even take it a step further (**if you feel comfortable**) and test the backup/restore processes. This is what I did with Aomei Free and I liked the software so much I sprung for the lifetime of the pro. I also liked Acronis True Image so much that I went for the 2017 version and got a free upgrade to 2018 through their current promotion that is still active. This was after using the free version of Acronis True Image for Seagate and Western Digital users.
Excellent questions! Keep them coming!