I think if it is a very large cock, and the woman is tight enough to have trouble taking it, it helps to have a head which is smaller, so the initial penetration is easier.
If the cock (at least, from my perspective) is slightly-above-average or smaller, then a large head is desirable, because I like the way it feels against my G spot and cervix.
I think my new partner is the first man I've been with who has a large cock with a substantial head (see Exhibits A & B), and his shaft also widens toward the base. Usually, when we start fucking, I'm not taking all of his length, but as I get more aroused and tented, I eventually can take all of him, and I love the combination of intense stretching at my entrance right at the time as his thick head bottoms out in me.
What a fucking incredible sensation!
Exhibit A
Exhibit B
(He thinks I'm a lot of fun, too). :wink: