As of April 15th 2019, my favorite software (besides from Simple DNS Plus and Simple Failover) is:
Desktop software / Utilities
VirtualBox - https://www.virtualbox.org
Amazing virtual machine software for the desktop.
I prefer to use this over Hyper-V (which comes with Windows 10 Pro) because it is much easier to move virtual machines between host computers. I simply store the VM images on a portable harddisk and move this between host machines as needed. This is possible because VirtualBox (like VMWare Workstation) is a "level 2" hypervisor - meaning that hardware is virtualized. Hyper-V is "level 1" meaning that VMs interface directly with the hardware, and thus are much harder to move to a different host machine.
I used VMWare Workstation for man years, but VirtualBox does exactly the same, only for free.
DropBox - http://www.dropbox.com
Just the best. I have tried switching to Microsoft's OneDrive a few times actually (it offers more free GBs and integration with online Office programs), but I keep coming back to Dropbox because it just works better.
KeePass Password Safe - http://keepass.info
Great (free) program for storing passwords.
Storing the (encrypted) password database on DropBox makes it easy to sync between computers and my (Android) phone.
CutePDF Professional - http://www.cutepdf.com
I mostly use it for scanning to PDF files, and for merging multiple PDF files into one.
TreeSize Free - https://www.jam-software.com/treesize_free
Figure out what is using all that hard disk space.
Macrium Reflect - http://www.macrium.com
Great software for cloning / migrating harddisks.
SyncBackPro - http://www.2brightsparks.com
For synchronizing folders, uploading websites, backing up cloud storage, etc.
FileZilla Client - https://filezilla-project.org
Super FTP client.
CloudBerry Backup - https://www.cloudberrylab.com/backup.aspx
For backing up PCs to the cloud. Using this with Amazon S3.
VeraCrypt - https://www.veracrypt.fr
For making an virtual encrypted harddisk - which lives in a file on your regular harddisk.
Better and cheaper than BitLocker - better because I don't have to encrypt the whole disk (which could cause others problems) and cheaper because it is free and BitLocker only comes with Windows 10 Pro.
This is where I keep source code / Git repositories on my laptop. If someone steals the laptop, at least this stuff is safe.
7-Zip - http://www.7-zip.org
Great for working with zip files and other compressed file archives.
I primarily use this because the built-in function for creating zip files in Windows 10 doesn't work with file names containing non-english characters.
Photography / graphics / video
Trello - http://www.trello.com
Fantastic for organizing thoughts, todo-lists, and everything else. With apps for Android and iOS.
GitHub - https://github.com
THE Git respository site for open source.
Hosting all our open source stuff here.
BitBucket - https://bitbucket.org
Nice Git respository site - free, also for for closed source, for up to 5 users.
Hosting all our closed source stuff here.
Exchange online / Office 365 - http://office.com
Hosted e-mail for your own domain names.
StackEdit - https://stackedit.io
Great markdown text editor in the browser - which means spell check included.
I have tried many different tools in all these categories over the years, and I can highly recommend all of the above over any competitors that I know of.
If you know of any better alternatives please do tell me in the comments below - always looking for better toys :-)