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I use TWC + Max the most along with Radar Scope and Weather Alert for very timely warning info.

Used to use weatherbug didn't like the interface as well after comparing several other data sources to theirs I realized the data was badly delayed and or inaccurate.

I use twc, but wish the default screen would be local instead of selection screen
 
I use weather channel because the iPhones is powered by them and I fined it accurate and expansive although slow to start up.
 
Hmm, I guess I'm in the minority of preferring accuweather's simple, stylized interface (free version) for quick checks. I do agree their forecasting is often more wishful thinking than anything, though.

I like it too. I bought it for the iPhone and the iPad. I think it looks great.
 
Weatherbug is what I have. It went from paid to free and I think it's still free. It's real neat and they have a camera for Chicago Ill in front of Wrigley Field which makes me giddy.
 
I use the Weather Channel. Simple and clean. Accuweather IMO is not laid out very well and can be confusing (though it looks nice).
 
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