Honestly that to me seems like the problem. The Cowboys on paper seem like a great fit.... but Jerry Jones is a control freak and wants total control which is going to be an issue with Bill. Also we don't know if Jones will keep McCarthy for another year.
The Giants are obviously a sweetheart team for Bill, but they are so down right now that it's a total rebuild, and we saw how Bill's last rebuild went. If he wants to go somewhere, win, and chase the wins record, that's not an ideal spot.
Bill has to be selective when taking an NFL job. He's 73 and getting fired again probably means he's done for good. He's also not going to have the same level of rope he had in NE with a pedigree of winning and and a grateful fanbase that is sentimental towards him. If he takes an NFL spot, he needs to really feel confidant that it's a fit.