I think it's interesting when people say LV is more common than Chanel, I mean isn't this just a given? If we factor in the cheapest bag of both brands, it goes without saying that many more can afford LV compared to Chanel. My question is; why would this influence whether you prefer one brand to another? To my knowledge, you prefer a brand because of its product offering and whether it fits/suits with you and your lifestyle, not whether it's been seen on X, Y & Z. Perhaps I'm wrong?
In regards to the original question, I do agree with many posters that Chanel requires a dressier outfit however I think most, if not all of these posters are basing this on the elusive Classic Flap/2.55/Reissue. There are many Chanel handbags that are equally as casual as LV (think Coco Cocoon) and equally as many LV bags that are dressy like Chanels. What I'm trying to say is that it is relative, we buy what we like.
I suspect there are many LV buyers who buy predominantly the more casual bags such as Speedy, Eva (granted, this is debatable on how its worn), Neverfull and there are others who buy the dressier bags such as Sobe, Limelight, Brea etc.
I would say it's hard to choose between the two because they both offer a wide selection of products aimed at niches in the market, but not necessarily the same market. One poster mentioned earlier they preferred LV for variety but Chanel for elegance, and this is perfectly put. I think LV go for more of a 'fashion forward' crowd, particularly with their seasonal offerings whereas Chanel aims for women who are after a lot of investment for their money.
Just my opinion.