Which E.D. medication (cialis, levitra, or viagra) works better?

I have heard that cialis is more effective on an empty or full stomach whereas viagra needs to have an empty stomach to be more effective.

Viagra is the first medication in a group called 5-PDEI it is non selective drug i.e. it will inhibit the enzyme PDE all over the body including the heart enzyme hence its not recommended for cardiac patient also it has delayed onset of action 2 hours and 24 hours duration of action
cialis and levitra are the second generation of the 5-PDEI it is more selective i.e. cause erection only with rapid onset of action 30 minuets and a duration of action more than 36 hours i.e. you can take cialis or levitra in the morning and have sex at night while viagra should be taken 2 hours before sex in addition viagra absorption is affected by the presence of food in the stomach while the absorption of cialis and levitra is not affected by the food