Well, Windows 7 is slowly becoming a dated operating system. First released in 2009. Windows 10 is a more modern OS with some nice new functionality. It focuses more on the cloud first principle and has support for universal windows apps.
For the moment the choice simply is yours. MS would prefer you upgrade. Should you ever decide to upgrade your computer to a new Intel Skylake processor MS wil only support you if you have Windows 10.
But be warned, Windows 10 is a bit different from 7. The start menu looks different and notifications are all found in a new side bar. I’ve come to prefer W10 over 7 but some people are more critical.
I would suggest you give it a try (and not just a few hours, but a few weeks). In your first month you should be able to undo the upgrade and go back to your previous 7 install. After a month, Windows will delete the backup it has made of your previous windows install.