In my opinion, create your own. This way, you learn more about the business you are in, and do things the way you want them done. While an established website may help you achieve a profit quicker, it will certainly not be as fullfilling as one created by yourself.
Yes start from scratch. We did and it is better as PaidPost says. Unless of course that site you buy is a natural keyword .com domain name with high organic traffic then buy it because it is going to take a lot more time to buildout your own YoYo968. Logic
If you are new to this field, buy an established website that is already making consistent revenue. Make sure you requests stats and screen shots when asking for a site too.
Its always better to make your own in my eyes. Watching it all start from the beginning and watching it grow instead of having someone elses creation.
My opinion - From Scratch The nice thing about that is, your only paying for the domain and the servers, your not paying someone else for the domain name and your not paying huge from someone else work. Starting from scratch you know everything that has and will happen to your site, when you buy one (unless you do some hardcore research) there could be lots of thing that you don't know about the site that could come back and bit you hard.
I would say create your own, only because traffic is so easy to purchase and artificially inflate numbers with and it is bound to be a selling point for most sites.
If you're new to all of this, i think it is better to create a site from scratch so you can learn all the little stuff along the way. But you're experienced and are looking for a new project (and have the money) buying an established site is better in my opinion.
According to me starting from scratch and building the website would be best option. But then you will need to spend time in marketing, promoting, etc, etc. If your looking for something quick then you can pick some ready to go sites. Its upto you how you want to go about..