I believe this answer changes based on length:
- For the "shorter" penis (under 5"), additional length is what would be preferred;
- For an average length rod (5-6"), length or girth additions would be appreciated about equally (averaged across all 'penis desirers');
- For the longer phallus (7"+), it is more common for additional girth to be generally preferable once "hitting the back wall" becomes a realistic possibility when "parking in the flesh garage".
There are theories that this 'bell curve' of preference may have a secondary prominence for wangers above 11" in length: where physical limits cease to be a primary concern, the preference may revert to length (trying to beat local recorded maximums) before again turning back to girth (for the same reasons) somewhere in the 13-14" range.
Please note that the above is a relative scale, primarily based on what one is "used to" or "readily able to acquire".
The definition of what constitutes a "big" man-cannon, as well, is based on similar relativity… Though, as an average, a man should feel no qualms in considering themselves "well endowed" if they meet one or more of the following qualifications:
- cannot fit their engorged wiener fully into a US standard-sized toilet paper roll tube.
- can invert a standard "Guiness-style" pint beer glass over their unit when erect, and "touch bottom" with the tip.
- using a tape measure, measure either 7" in length, or 7" in schlongile circumference when fully aroused.
As a side note, it is important for baloney-pony enfatuated women especially to understand the "grower versus shower" principle of dong size – there are a shocking number of women who have either never heard of the difference, or who have never experienced a "grower" in their own personal experience or casual pornographic film viewing, and thus make mistaken assumptions about potential pleasuring power of men who are simply under- or non-hornified at the time of viewing. This does not seem to apply as strictly to gay or bisexual men, who generally have some experience in sidelong-glancing the at-rest cockadoodle noodles of their fellows.