To put it simply Bitcoin is decentralized and not controlled by banks which is why it is favoured in the community but Ripple is aimed at being used by banks instead of their old way of transferring funds like SWIFT which has high charges and takes days, Ripple will be cheap and enable the transaction within seconds. Some people are against Ripple because it has anything to do with banks which is against what Bitcoin is trying to do. That said, I think they are both good for the future mainstream of cryptocurrency.