This question depends upon a number of things, the first and foremost, is what is your goal for the content you want to get?
If your goal is to throw something up quickly and not really care about what it effect it is
going to have, then the best way to get content is to just get some PLR content that is very common on the web and throw that up on your website. It fill it in nicely, you didn't have to create it and it saves time...
However, your content isn't unique and it doesn't reflect your expertise, personality and skill in that particular niche.

If your purpose for getting the content is to build a relationship with your visitors, keep them coming back and then ultimately to promote your website as an authority website, then it is important that you have content that is unique and that was created by you. This process is the most time consuming but it has the best long term results. Bloggers that are making thousands of dollars a month on their blogs have been at it for a while and have been consistent at putting up unique content, but also giving a reason for people to come back. They put up useful content such as product reviews, opinions, controversial topics, etc. This process took a bit of time, but they are reaping the rewards for it now.

You can also have something that is in between the 2 scenarios listed above. That is to comment on someone else's content. There are a number of different ways that you can accomplish this, from commenting on other people's blog posts, to commenting on other people's articles, press releases, or web sites. A very useful tool for doing this is located here is called clipmarks. This tool is nice because it makes it easy to gather content from the web and allows you to comment on it (up to 1000 words). You can then post it to your website, or blog, which makes it very nice and convenient.

I hope this was helpful. Leave a comment if it was.