"good for you" vs. "worse"
We were talking about A7 vs. 6, and you wrote:
"the 10, J, Q, K do not change the value of the hand, so getting the A, 2, 3, 10, J, Q, K either improves your hand or does not change the value. 7 out of 13 cards are good for you. only 6 out of 13 will make the hand worse. The cards are in your favor to hit."
When you say 7 of 13 are "good for you", it is misleading. Actually only 3 of 13 are good for you, while 4 of 13 are "no effect".
Suppose I would have made the following argument, which is similar to yours.
"the 10, J, Q, K do not change the value of the hand, so getting the 4,5,6,7,8,9, 10, J, Q, K either makes your hand worse or does not change the value. 10 out of 13 cards are bad for you. only 3 out of 13 will make the hand better. The cards are in your favor to stand."
This argument is also flawed, because you can't count the 10's as either good or bad. They are "no effect". You should double only because you can get more money on the table. If you can't double, basic strategy is to stand.
Lefty
P.S. Just to be clear: we don't make hit/stand decisions just by counting the number of "good" vs "bad" cards. It's slightly more complicated than that. Here, I am only pointing out the flaw in what may seem to be an intuitive argument.