Sforno on Exodus 34:9/ספורנו על שמות ל״ד:ט׳

1כי עם קשה עורף הוא, and it will commit sins even if You will go in our midst. Even though I am fully aware that such sins, due to their being committed in Your immediate presence are more serious than otherwise, as You yourself have pointed out in 33,5, on balance I believe that it is still better that You Yourself should go with us.

2וסלחת לעוננו, seeing that only You are capable and willing to forgive and we constantly hope for Your forgiveness, the angel should not be the one going with us even though countermanding his instructions is a lesser sin than countermanding Your instructions. After all, there is no hope at all to obtain forgiveness for disobedience committed against the angel, as You Yourself pointed out in 23,21 “for he will not forgive your sins committed due to a rebellious spirit.”