This is a brief breakdown of the most popular and commonly used Desktop environments to refer others to in the instance of shaming or boasting about ones desktop environment... Categorized by date of release and resource usage along with additional details. I used a base install of Debian for each installation with the DE, then wiping and re installing for the next DE. The only active window was the default terminal installed to minimize skewed results due to poor program optimization. The results are rounded to the nearest 10 MiB since on most machines these changes are admissible.
Being in the lower end of the specs, at or around 100 MiB of usage. I noticed with these DE that boot up was very snappy, ranging from 5-10 seconds from boot to terminal. These lower spec DEs also have a common focus on a Mouse Centered work-flow. In this category based on resources and looks, I would recommend XFCE to start and if you need to keep the looks of a proper desktop but need to squeak out a bit power from you system, Enlightenment is a great option.
These are our heavier usage DEs, these often show ram spikes at about 150 - 300 MiB. Boot times vary, ranging from 20-45 seconds to terminal. I have noticed a trend with these DEs as well that follow a more Keyboard Centered design for easier work-flow. Though this may just be a product of their more Tablet Oriented design. In this category their is not much variety in regards to looks. All are clean and look like a modern desktop. Though I would recommend either Mate for a Classic Gnome feel, or if you are coming from Windows and need a familiar space. Or Gnome for those wanting to feel what modern Gnu-Linux is like.