When there are values in the variables, the lines seem unnecessary. But when the variables have no values, they look “off to the right”. I do like this most recent layout though. Inclined towards no lines, personally. The visual clutter bothers me more than any sense of “off-center”.
Another idea: don’t try to center this. Left-justify it.
A 1234 X 1234
B 1234 Y 23444
C -1234 Z -120
D -120 T 1234