I'm a picky bastard when it comes to my windshield, visibility and the wipers. In a little over 1 yr of owning the car, I'm on my 3.5th set of wipers (stock, replaced once, then just the passenger one, then winter set, then brand new set in April).
From what I've heard, the expensive BOSCH stuff is not all that better at all. The wiper I like best is the Rain-X brand wiper (available at Walmart). The TripleEdge WalMart stuff also works well (right now I have one Rain-X, one TripleEdge because they didn't have both 21" and 19" sizes in both). The difference in terms of wiping quality is pretty small. Rain-X one is more aerodynamic, so it lifts less off the windshield.
In my experience, windshield wipers go thru three stages: excellent wiping for first two, three months, then average wiping for 8 months or a year, then they start breaking down and wipe worse and worse (as far as I'm concerned). Honest, though, I haven't had any set of wipers for more than 4 months yet, and they all get bad enough after 4 months for my taste.
So I figure: screw spending money on $15+ wipers. I go to WalMart, shell out $14-16 for the pair, and I'm happy for three months. Total cost of wipers per year: $64, if changed every three months. Glad to pay that much for good visibility.