both are currently priced about the same (400 ish dollars) with the s23FE on sale for black friday , I am trying to go back to samsung after getting tired of the pixel 6A but I am on a budget , it looks like the S21 ultra is better in almost every way on paper but the S23FE is much newer so im struggling to decide , if it helps any the samsung S10+ is my favorite phone of all time i only switched to pixel when it broke
why dont you wait a little longer the new ones are coming out soon and prices are going down
if i buy amazon refurb s21U i can just return it within 90 days and buy the 23 ultra if it indeed does drop in price