From the installation process you have two options, KDE and Gnome. KDE is my preference mostly because I just happen to like the look and feel as well as the tight integration of the interface.
Should you not like how “heavy” those desktops are as they are more resource hungry than some would prefer there are some Alternative Light Weight Desktops, two of which I have a good amount of experience.
LXQt
Has a similar look and feel as KDE Plasma Desktop but without many of the extra bells and whistles. Of the light weight desktops, this one is my preference.
More information on can be obtained at the official LXQt Website
To take this Desktop Environment for a spin on openSUSE, install instructions here form the openSUSE Wiki
MATE
The MATE Desktop is another excellent lightweight yet attractive classic desktop experience for openSUSE users. It has a bit of a Mac OS X feel to it for those that prefer that look. The key hear is, it is it feels efficient and will work extremely well on older hardware.
For more information, you can check MATE Desktop official web page.
This desktop environment works very well with openSUSE and if you would like to try this instead of KDE or Gnome, install it using these instructions. Pay attention to the version number. I recommend you install the latest version of openSUSE Leap and therefore install the build of MATE from the Leap section of instructions.
Other Desktops
There are a lot of really great Desktops that many enjoy using. I currently only have experience with the aforementioned two. Xfce is another one that all the kids are talking about. I haven’t spent much time with it so I can’t really say anything useful about it.