May i know which Spectra Pump is good. s1 or s2 Thanks

I'm using S1. 1) It has a built in battery and can last me for 1 day when I'm out 2) hospital grade pump 3) good suction (I have experienced clog ducts twice and managed to clear by using S1). Even my lactation consultant recommends S1 too. But it's quite bulky though!