which one is more natural?

I hope you had unforgettable memories.

I hope you made unforgettable memories.

This one is a bit debatable, but I'm going to say "made" is more natural. The reason is that "had" is past tense, and memories are something that remain with you (especially if they're unforgettable). Therefore, if you still have a memory, using past tense would be a little strange.

Depending on the situation, "I hope you made..." could feel very natural, but in a certain context it could be more correct to say "I hope you have unforgettable memories." Context is key here.