I have both Flickr and SmugMug accounts, and much prefer SmugMug. You have greater choice of display formats and customization, no bandwidth limits, easier ability to display photos large size, and more secure backups. (Though admittedly, with a $24.95/year Flickr "Pro" account you do get more.) Flickr is also better if you want a huge number of people to be able to access your photos and want to be a member of special interest groups. So it all depends on what you want from a photo hosting site, really...