Your question is ambigious. Are you asking what a different system would look like, or how we would get there?

As for the first question, there are many obvious ways to improve the system. Here are some suggestions: abolish the electoral college, abolish the Presidential veto and pardon, abolish the Senate, abolish lifetime Supreme Court terms, add term limits for Congress, publicly fund political campaigns and outlaw campaign contributions as illegal bribery, allow public recall campaigns against the President, Congress, and Supreme Court, etc.

As for the second question: "The biggest problem with the US is that we haven't had a political revolution in 250 years."