I would vote both Gen 2 and Gen 3. My number one favorites are both the Moon Ball and Timer Ball. The Moon Ball is perfect for dark and ghost types, which are my favorites. The Timer Ball has both a cool exterior design and release animation.
Other favorite designs are the Premiere, Luxury, Lure, and Beast Balls. When I was still breeding competitive Pokémon in gen 7, I, most times than not, tried to breed them specifically to be kept in one of those 6 designs.
Other favorite designs are the Premiere, Luxury, Lure, and Beast Balls. When I was still breeding competitive Pokémon in gen 7, I, most times than not, tried to breed them specifically to be kept in one of those 6 designs.