Obviously some guys want to be bigger no matter what, but personally I don't desire a larger size. Sure, I've had the occasional fantasy (while horny) of being bigger, and girls writhing in pleasure upon seeing/working it. But I know that in reality being any bigger would be unlikely to be advantageous (not to insult the ladies who prefer larger).
I'm already bigger than over 99% of adult males at 8.25" L x 6" G. That's volume wise, well over twice the size of the majority of men (according to the latest studies). Many women could take larger than me (although for some it may take many weeks of practice), but being larger would inevitably decrease the number.
Additional Info (you may skip the rest of this):
What many people don't realize is that the majority of men are below average in size. The small minority of men that are much larger than typical throw the numbers off. Any clinically done study (were they actually measure the penis), has come up with average numbers of less than 6" length (an average which is larger than the majority of men, as I explained earlier).
One of the studies showing the largest average size (of 5.877 " L) found the commonly believed typical size of 6" is actually in the 70th percentile. We're talking a fraction of an inch here, but reality is that for the vast majority of men there is a variation of less than 1" length and less than 1/2" girth.
Less than 1% are over 8 inches in length, and that doesn't count a combination of length and girth which would bring the percentage down a lot more (although there is likely some correlation between length and width). If you look at this worldwide there would be tens of millions of men my size or larger (although way less than 1 in 100 men), explaining how a site like this has a feasible purpose.