When Stellar's codebase was still just a fork of Ripple (entire codebase was completely re-written from scratch in 2015), it experienced many divergent forks of the network due to weaknesses in the Ripple consensus protocol. Those weaknesses have been eliminated in the new SCP described in this paper, but AFAIK Ripple still has these systemic problems. The new Stellar codebase is actually a joy to work with.