Correct me, if I'm wrong:
Ripple was developped and held (50%) by a company, wasn't it?
In this case I absolutely prefer bitcoin.
Are there some control mechanism to prevent price manipulation by their own company?
You're talking about the currency inside the Ripple payment system, often called XRP. That's really not intended to be used as a means of exchange or a store of value (at least in the near term), so it's not really fair to compare it to Bitcoin (which is).
Yet funnily enough its the way the company behind Opencoin was to generate revenue (not to mention individuals within to generate a personal wealth...no?)

Don't confuse the system with the revenue model. Google is good if it's a really good search engine. Google makes money if it generates really good ad revenue. But it would be kind of odd to judge Google as a search engine based on its ability to generate ad revenue.
To carry the analogy a bit too far, the way Google might think about it is like this -- if we make a really good search engine, it will generate lots of ad revenue. So if you care about the long term, you design it to be a great search engine and judge design decisions based on that, not on their affect on revenue.
Ripple was designed to be a great payment system and to federate existing payments systems. It also has features to support social/community credit and other types of possible future economic activity. We weren't trying to build something whose primary purpose was to generate revenue for us. Those priorities are reflected in the design.
If you build something whose primary purpose is to make you money, there's a good chance nobody will ever use it. And if you try to decentralize it, it will fail because there's no shared goal to make you money.
Build something great first.
Nice rhetoric. Too bad it's all bullshit considering Ripple is a centralized premine scam intended to make Jed and its' founders incredibly wealthy. You know it's not winning over the public if they have to send their employees to write replies, knowingly that nobody in the public is going to root for them.