I am looking for a relatively easy way to generate the following 3D graphics (In Windows, or Linux):
I appreciate any recommendations
Since the graphic is isometric, it seems you don't need a too realistic drawing. In that case, I would use Inkscape. Inkscape it not a 3D tool, it's a 2D tool. But as you'll see you can get a 3D-like result.
Inkscape is gratis and creates vector graphics that have good quality and can be exported to pixel graphics.
If you want a flat look, best use an angle that is a multiple of 15°. Doing so will simplify later changes which require the same angle. Getting a multiple of 15° can be achieved by holding the Ctrl key. Remember the angle for later changes. An angle of 30° looks just right.
Duplicate (Ctrl+D) and flip (H) it to create the right side of a cube.
Enable snapping to edges and move it until it snaps
Getting the correct angle is best achieved by holding the Ctrl key, which snaps every 15°.
Set fill color to and adjust line weights as needed
Add the text
Center vertically and horizontally over a side using these alignment buttons
Create two duplicates of the text (Ctrl+D)
Move the duplicates to their sides and center them
To get a flat look, take these steps (this was edited later, so it will not show up like this in future steps):
a) shear the left text by the same amount of degrees as you did for the rectangle:
b) shear the right text by the same amount in the opposite direction:
c) the most difficult part is on the top, also because there are two options. Either shear as for the left text and then rotate counter-clockwise. Or shear as for the right text and then rotate clockwise. The rotation angle is 90 minus the angle used for shearing in step 2. The effect is best observed with a number that has a flat bottom. Thus I chose the number 2. The bottom of the text should clearly aligh with the edge of the cube.
Mark all 6 items (3 sides and 3 text) and group them (Ctrl+G) to keep the arrangement.
Duplicate the cube (Ctrl+D) and move the duplicate to the next position, snapping at edges. Go from bottom to top first. In the particular example, build 4 cubes.
Change the texts
Add axes and labels
The process seems slow in the beginning, but as you can see, it's quite fast in the end. The whole process took 49 minutes, including the creation of screenshots and writing this answer.
For flat axis labels, shear and rotate similarly as for the cube descriptions.