S1+ it's hospital grade pump and it really clear my boobs well. I have s9+ too I bring it when I'm out. it's not as good as S1. the difference between s9 and s9+ is one has inbuilt battery which is s9 plus. s9 don't have inbuilt battery you need to find electric point whenever you want to pump
I personally prefer spectra s1+. It’s pretty bulky, but that is the only pump that can empty my boobs well