I have Cyclemeter as my main app I have been using. I just downloaded Endomondo and trying it out, it also looks quite good. I have map my ride also but like Cyclemeter better.
Of course I have the mapping app that comes with the phone and Google (my map). I really like to keep MotionX GPS on the phone also as it doesn’t require connection for the GPS to display maps as they can be downloaded in advance. Some people don’t know that the iPhone refreshes the maps as you go and when you get into a poor connection area maps will load slow or not at all. Programs like MotionX are a good fix for that. If you don’t have that type of a app you can view maps in advance of the area you know is a problem and the phone will keep that map in a temp file for a few days. Little trick I didn’t know that comes in handy.