Don't forget that if you go with a town car, you will have to stop and get your luggage before you are on your way. And to me, that is the best thing about ME, the fact that I don't have to handle my checked bags.
We have done the ME/Garden Grocer combo a few times, and it has worked very well. I buy just what I know we will use, so I don't end up with a ton of wasted food or too much junk food. You can order things like apples, bananas, and granola bars.
If I was on a short trip, didn't check any bags, and didn't need any groceries, I would go with a town car. Otherwise, I like using ME and Garden Grocer.