My favorites for iOS are all Swift apps:

• Arctic: !arctic@lemmy.world (incredible smooth performance and feels like Apollo)
• Avelon: !avelon@lemm.ee (great features like gallery slideshow view inside posts for images and individual hide read posts settings)
• Mlem: !mlem@lemmy.ml (many customization options including unique ones like rearranging vote/save/… buttons in a widget style)