When Bernie Sanders began his campaign, he was running as a protest candidate. Historically, candidates like Sanders, Denis Kucinich and Ralph Nader on the left and Ron Paul on the right have served to give voice to the less mainstream members of their parties. Sanders forced Clinton to confront issues like international trade, the wealth gap and others that she may have otherwise been free to ignore.
No, I do not think that Bernie Sanders makes a better candidate than Hillary Clinton because Clinton is arguably the most qualified presidential candidate in American history. Sanders is considered radical and idealistic by many people, but he has helped bring important issues such as income inequality and free education to the limelight.
Bernie Sanders did not make Hillary Clinton a better candidate. She is an experienced politician and debater, and would have been well prepared in the general election, regardless of her primary opponent. Clinton is also well versed in the issues. His personal attacks hurt her, particularly coming from another Democrat.
Bernie Sanders does not make Hillary Clinton a better candidate, it rather underscores his extremism and radicalism relative to his socialist underpinnings. To his credit he comes by his socialism honestly, which is more then can be said for Hillary. She will do and say anything to be elected president.