I was with smugmug, but found it too cumbersome to add new galleries, and I wasn't happy with the print quality (at the time they ignored your color settings and used their own).
Switched to
Zenfolio | hosting service for photo galleries | a place to learn and enjoy photography last year and am pretty happy with it. Not quite as much look and feel customization available, but setting up new galleries is a breeze and I never have to write CSS & javascript the way Smugmug seemed to require.
Zen also give multiple fulfillment shops for printing or the option to do your own order fulfillment (meaning you do your own printing to fill orders.)
I found
Photo hosting. Sell photos. Photography websites. | PhotoShelter recently and would probably go with them if I were launching now. They seem best set up to sell stock directly from your own site. They have a Webinar to demonstrate setup and features.
At the very least, you should look on photoshelter's site for a report with survey results discussing what photo buyers like & dis-like about photo sites. Very helpful in deciding on your website design.
regards,
-t