“He who is commanded and does is greater than he who is not commanded and does” (Kidushin 31a). We should interpret that “commanded and does” means Lishma [for Her sake], and “not commanded and does” means Lo Lishma [not for Her sake].
Because he is not working for the sake of the Creator, it means that he is not performing the Mitzva [commandment] because he has a commander commanding him to do the Mitzva, since the Commander does not obligate him to do. That is, the Commander is not the cause of his performing the Mitzva, but rather the Lo Lishma is the cause. It follows that he has no commander.
Hence, one whose cause to perform the commandment is the Commander, meaning the Creator, is certainly greater because the Lo Lishma has merit in that it brings him to Lishma, but Lishma is certainly greater than Lo Lishma.