For my Galaxy life, I had the s3,s4,s6,s7, Note 8, Note 9. I always tested fluidity with a new phone by testing how choppy the scrolling is in google maps, compared to the smoothness of google maps on the Iphone. Unlike the Iphones google maps 60fps scrolling ,you could pretty much know that if the maps scrolls under 60fps , then most other swiping and scrolling is going to be just as bad.
The s3, and s4 = fluidity lag. Didn't try the s5. The S6 edge was a breath of fresh air, and was very close to fluidity of my Iphone 6. But still had that lag. The s7 edge, was a step backwards, and side by side in maps, the s6 edge had better fluidity. Returned the s7 edge, for a replacement, but in testing maps and other scrolling in the UI, the replacement wasn't any better. The s6 was just better in fluidity. Disappointed, I returned the s7 for a refund, and held on to the s6 until the Note 8.
The Note 8 was the first android phone for me, that I can say, for the first time matched the Iphone in smoothness. After having three replacements of my Note 8 because of a black dot flaw manufacter defect, I was giving a Note 9 as a replacement. The Note 9s fluidity matches my Iphone and my ipad, and besides the nicer animations of the latter, I can't tell the difference. Samsung has caught up in this regard, and the disadvantage it once had is no more. Now if they can just make the animations as beautiful.