Sweeden/Denmark/Switzerland are all great examples of the best type of democratic system, so I was also thinking of those if I wanted to go that route.
L2R: There are certain specific criteria that determine exactly how democratic a state is. Some factors increase the level of democracy and some decrease it. Things like the type of economy, voting legitimacy, freedom of press/speech and wealth distribution are some of the more important factors to look for.
A big reason the US is less democratic than some other systems is because we still have a lot of the old traditions handed down by the constitution. In the US the presidency is not a popular vote mainly because it wasn't feasible during the time the constitution was written, election by delegates is markedly less democratic than by popular vote. Also written into the constitution is a law that makes it very difficult to change the constitution. Not only do you need massive public support for a constitutional amendment, you also need 2/3 of both the house and senate and the president behind it. The process is designed to be nigh impossible which is the reason why things like election by delegates still exist today.
You Aussies use open ballot preferential voting system, one of the best systems in the world in my opinion. You get to rank candidates by your preference and choose from any party. Its downfall is that it requires voters to be knowledgeable enough to rank candidates accurately. It is very different than states like the US where you can only chose one candidate, or like in the UK where you choose a party and the party chooses the Prime Minister.