Unlike Eric, I'm completely ambivalent about Target. I generally find myself at Wal-Mart much more often than I do at Target. I'll give Target the nod for having stores that are cleaner, more organized and generally nicer, but I'll also say that I'll buy a whole lot more at Wal-Mart.
The strange thing is that it's not just the style of store, because I typically prefer Lowe's over Home Depot, for almost the exact same reason. Maybe I like the color of blue over red (or orange).
There are some places that Target excels over Wal-Mart, namely in cleaning supplies. Target has a monstrous selection of things like mops and brooms and, dare I say, plungers, where Wal-Mart has a few, but nothing like Target.
Other than that, I find that I'll get almost everything that I need from Wal-Mart, because it's usually more convenient to me. Other than selection, I find that the staff is about evenly matched, so it comes down to what I can get in the fewest trips, and Wally World gets the nod.