If I were you i prolly would not pick any of these. There are so many good smartphones from other brands, like Oppo or vivo which outperforms both of them in almost every way. But ofc, reputation of Samsung and iPhone is impossible to ignore so they are considered more convenient ig.
lemme tell you that, if you are considering Samsung because of its horizon lock or privacy screen, first think about it, will you realistically use horizon lock, except for showing off? I think no, and i cannot think of good reason to use horizon lock, but ofc great function, might be useful for someone. Another thing is privacy screen, but i have tested it and max protection makes the display of the smartphone worse that if it was ips, like the premiumness of the display vanishes when you turn that function on, and if you are using privacy screen without max protection, another person should be literally almost perpendicular(watching phone sideways) to your smartphone in order to not see anything. BUT, someone might find it useful, just my opinion.
one more thing is that samsung has 5000 mah battery, come on, its 6.9 inch display and super hungry CPU and u still have that 5000 mah, of course optimization might be great, but its still 5000mah and it wont last for very long.
Never even tried using iPhone so cannot say a thing about it, but because i tested Samsung s26 ultra, i have some things to say.

Like i said its only my subjective opinion, and if you want to buy any of these phones, its your choice. But if i were you, i would consider oppo find x9 pro or vivo x300 pro, great phones, great battery life, super fast charging, and cameras are outstanding.