Easier to start with a 20 gallon if you have the room. Contrary to your believe, a 20 gallon is easier than a 10 gallon to maintain.
The basic equipements are almost identical, so $$$ cost will be the same. More choice of fish (and corals) with a larger tank too.
Start with a budget first. Tell us what you are planning to keep in there. Just fish? or corals?