My experience is the Met Office is often the least accurate for me!Anybody from the UK reading this? A big issue with a lot of these apps is that they use third-rate weather services that don't have the accuracy, knowledge or reputation of the Met Office. Are there any weather apps (aside from the Met Office's own) that use Met Office data? Even the BBC doesn't nowadays.
it very much depends on where you live though I think.
My personal favourite is WeatherPro from Meteo Group - they do the BBC weather.
Locally to me it always seems to be the most accurate and the layout is clear and concise.
I do however use Carrot as well, with Apple Weather api currently set.