We have both, i went from the S7+ (now my wifes), to an S8 Ultra (now my sons), I moved to a Laptop the Book2Pro.
S8 Ultra is amazing, especially coupled with the matching keyboard case.
I would go with OneDrive as is has better Samsung integration, key one being Gallery sync, add O365 you will begin to ask why do I need a laptop/pc.
ZFold4 [Mobile], Pro5 [Watch], S8 Ultra [Tablet], Book2 Pro i5 5G [Laptop], Buds Pro2 [Buds] M70A 32/43" [Monitor], Smart Tags+, iPad Mini 5 and iPad Pro 12.9 GEN2 [Tablets], Dell Inspiron G5 Laptop
ZFlip3 and ZFlip4 [Mobile], Watch5 40mm and 46mm [Watch], S7+ and S6 Lite [Tablet], QN95A [TV], Q900A [Soundbar], MC28M6075 and MC32K7055 [Microwave], Jet 75 Complete (Vaccum), Samsung Level [Speaker], Buds Pro [Buds], iPhone 12, iPad Air 2, Air tags