In US sizing, I'm generally a 12E. A sidi 47 fits me well length-wise, a bit snug width-wise, can be uncomfortable after a few hours of riding due to foot swelling. The Sidi mega, however, was waaay too wide for me, like my feet were swimming in them. Diadoras run a bit wider than regular Sidi, I have a pair of Ergo Carbons I wear in bad weather, no discomfort. My most recent pair of shoes are Lake cx330-c. Absolutely the most comfortable cycling shoe I've ever had the pleasure to put on my feet. A nice stiff sole, soft "kangaroo" leather upper, Boa lacing that I can adjust on the fly...I love these shoes. Got them from Sun & Ski for $150, best money I ever spent on cycling crap.
Shoes to avoid for those with a wide foot...Adidas. I received a pair as a gift, and they run super-narrow. Don't know if they offer a wide width, or even if they offer cycling shoes at all, anymore.