It's both.
The people wanted Saul because he looked kingly.
He was tall and good looking.
He came from money and stature.
God appointed Saul, but he was not God's real choice.
God's choice of king of Israel would come from the tribe of Judah.
God gave the people what they wanted, but with a warning.
So once again, they turned their backs on God in favor of a man and to be like the pagan nations around them.
AGain... this does not say what has long been proposed.
If anything, the people chose to have a king besides God.
So God gave them a king they deserved.
But it never said that Saul was chosen by the people nor did it say that they chose him based on his looks or stature.
Considering the way David treated Saul as presented in Samuel (benevolent), it should not surprise us that the political motive behind it was to show that Saul was never mistreated or ill-conceived nor was he ousted from his throne by David.
The negative picture of Saul was of his own actions and words.
The writer of Samuel had a clear motive behind mentioning certain things, even mentioning similar stories often (David sparing Saul's life 2 x's).
Read in that light, in it is no wonder why David's claim to the throne of Israel was left w/ little doubt.
He never once usurped.
And the one chronicling Saul in the book of Samuel was clearly unbiased in his presentation of Saul.
That is very important politically and theologically.
I think interpretations that jump to the conclusion that Saul was chosen by the people for his looks and stature is not only short-sighted (cause its not in the text) but misses the point of the book of Samuel.