2017 Domane SLR is a new design and IMHO is currently the better all around bike for road and gravel. I have a 2014 Synapse HiMod disc that I really like but would get the Domane today (accepts larger tires, has fender mounts, you can adjust seat tube flex). If all you ride is road and don't care about fender mounts then the Synapse is still a really nice bike.