Here are questions to ask your door to door service provider before you pick the one you want to use.
1. What is the cost for the quantity that you want to distribute
2. Do they offer GPS service at that quantity and does it cost extra?
3. How long will it take to distribute the quantity that you'll be ordering.
4. Do they deliver to houses only or do they also deliver to apartments (then decide which you want)
5. Will they pick up your flyers for you.
6. Do they put only your flyer on the door or do they put multiple flyers on the door (then decide if that even matters to you).
Check them out on Yelp and other review sites. None of them get great scores so look at the reviews and decide what applies.
Equally important is whether you get a good feeling from whoever you talk to. If you're not getting a good feeling, think twice about dealing with that person.
They won't be five star reviews, but at least see what the reviewers have to say.