Ripple is centralized.
No it's not. Their network is decentralized. Sure they have pre-mine, but so do we.
Because Ripples exchange is distributed as opposed to centralized, the whole concept of co-location becomes fundamentally different. There is simply no central location near which you would co-locate for a speed advantage. Ripple exists on servers around the world, and anyone can easily spin up their own copy of a Ripple server for free. (The code is open source.)
https://ripple.com/blog/ripples-distributed-exchange-and-the-high-frequency-trading-arms-race/Maybe there are many nodes but their solution to the byzantine generals problem is the same one that has been used for thousands of years, central authority. If the ripple foundation was ever compromised than ripple would not be able to continue without them. That is precisely the problem that bitcoin solved and ripple unsolved.