Honestly I just like dicks.
That is on film or paper. In real life, like many women it's the man attached to the penis that counts, if he's loving and considerate, I'm his.
I'll be honest and say that I haven't been with a smaller man but I've been with 4 Mr Averages, 1 Mr SlightlyBiggerThanAverage and 1 Mr Huge. I could only fit Mr Huge in with difficulty but most of the time he shot off at my entrance. Mr SlightlyBiggerThanAverage never got rock hard so again I had difficulty getting him in. The 4 Mr Averages varied in sexual skill from absolute nightmare to total bliss. Although they would have been within half an inch of each other in size the way they treated me made all the difference.
Mr Huge never lasted long enough for me to find out if I could orgasm from his penis so I don't really know if I could get as much pleasure from a big one as I do from my boyfriend who is the smallest of the Mr Averages but I doubt if I would. My boyfriend's dick is the perfect length to stimulate my G-spot and he is the only one that I've had vaginal orgasms with. I also enjoy being able to take his entire penis into my mouth, something I could never do with the two big ones.
Regarding women buying larger dildoes, I think that is more for the novelty rather than physical enjoyment. I've other women's comments on several forums and most seem to prefer smaller vibrators. I personally prefer to orgasm with something slim inside (usually just my own finger) rather than a big juicy dildo.