Ripple has by far the largest sell wall in place.
HALF the circulating supply of XRP is locked up by the founders. This not only cuts the REAL market cap in half (realistically), but also the amount in circulation. Even if a fraction of the Ripple founders holdings were to be injected into the market would be catastrophic to the current market price.
I believe in the idea behind XRP but I think the fact they hold half of the entire pot is a little bit suspect.
Correct me if I am wrong.