There is no guarantee that person would give you the bitcoin back once they see how much those can potentially be worth.
I had read some cases where family members have done this and refused to give access to the wallet where the bitcoins are held.
The second method you had mentioned would probably be better than trust anyone even a close family member with your bitcoin.
Have also read some cases where people have buried their flash drives which held bitcoin on in their backyards. Well secured from the elements of course.
I
dondidn't want to go into too much detail because malicious people can expose this kind of information. There must be someone you trust. If there really isn't, then don't use that option. Storing the flash drive in a different house etc. is a sensible choice. Burying it in the ground is also an option, but it brings other risks.
The main point is to remove instant access to your Bitcoin. That way, you can hold it for many years. Otherwise, when times get tough or the price skyrockets, the temptation to cash out can become too strong.