I've been on both recently. Service was not at all comparable. In fact we wrote reviews on both.
Food was ok on SS and just so-so on SB. More dining options didn't equate to better food.
And SS lacked any evening entertainment on the cruise I was on. Oh they had their singers who were good but I've seen better shows in my kid's high school performances. Plus there was a single destination lecturer on. Additionally because of Hurricane Fiona we wound up having more sea days than designated. (of course that's no one's fault,) On SS during that time what did they do for activities, classes, etc? CRICKETS. Good thing I brought my own book and needlework. Not even them suggesting a handiwork get-together. Now compare that to Crystal where if there's an unexpected sea day, they wind up with more classes, more lectures, etc.
As for SB? Great CD on the cruise we were on. Horrible SB square place to get a snack as nothing like the Bistro. Only dried out pre-made sandwiches, cookies and cakes. Coffee was excellent though. Fun sail aways and they definitely made it a fun time but if you're doing a cold weather cruise on SB good luck because to get everyone together to "party" (like in Crystal Cove, it had better be warm because it's all outdoors. Indoor facilities are too small for everyone.