Honestly, I would do neither.
The Titanic sinking caused major changes in safety regulations on ships, preventing much more deadly accidents in the future. Plus, there are some good movies and books about the sinking.
If JFK was never shot, he would have probably escalated The Vietnam War even further. It’s also likely that being the proud anti communist, he wounding have worsened relations between the USSR and America leading to a higher chance of nuclear war.