Great idea mocking the units up in foam first and its nice to see people making their own furniture to suit rather than buying something that’s near to what they want.
As for the choice between the two, I would definitely go for the larger unit (its almost the same as one that I worked on a few months ago but the drawer is in the bottom of the unit so the shelf is easier to reach from the bed).
One thing that throws the unit off, IMHO, is the fact that it is mounted to the wall.
There are lots of websites that you can buy furniture feet that just screw in to a unit like this. Alternatively they are easy to make, depending on the design you decide upon, but this is just personal preference.
I look forward to following the project as you progress