I'm bouncing between Atmosphere Weather and the Beta test of Weathr lately. The live tiles are similar for both.
My favorite overall is still Weatherbug, mainly because the radar data is animated. The two I mentioned above haven't implemented animated radars (yet).
Loved Accuweather until it started asking me to rate the app every time I opened it up...nothing would stop it...rating it or not, uninstall/reinstall, soft or hard reset. I rated it 1 star and moved to Weatherbug, and (now that it's got animated radar) Weathr Beta is my main.