Personally, I'm a fan of the smart cover. My leather unit that I purchased with my iPad 2 still looks fantastic. I know a lot of people don't like the fact that the rear is not protected, but I'm not fussed about that at all
Having got four iPads, originals and twos in he family I only consider all round leather cases for complete protection. I tried a smart cover on my iPad 2 but did not like it. It is in a drawer somewhere and will remain there.
I hope you like your 3... I played with one in my local Apple store and the display is amazing. Not tempting enough to buy one though. I'll wait for the next generation.