I do Cardio Trainer because I walk and use the phone like a pedometer and use it to figure out calories burned. The MyTracks is better for determining speed and elevation changes because it shows you on a graph. I am not sure yet about export as I am still working on that.
I have also tried SatSportsLog but that app crashed my droid when I tried to look at the satellite veiw of my route. Also have tried Journey Tracker but to me that didn't seem to have enough features.
Also, if you keep your droid in your pocket you may find that the GPS doesn't get your location as accurate as when it would be on your arm or in your hand. On some walks I have it in my pocket and the GPS shows me zig zagging around. Not normally a big deal but the zig zags add to the milage I supposedly did. My last walk the programs computed I walked at 4mph, which is insane. lol