One is the best player on the planet (LeBron) and the other might be in the top four of their position (Kyrie). Our team is set to win championships and I think LeBron is more likely the piece to do that than Kyrie in the immediate future. LeBron is healthier and may even have more left in the tank than Kyrie given his knee issues.
I get the counter argument, though. The age issue is real, and we'd have to move some parts to make it work; however, I think he will be playing top tier basketball for years to come despite his age and I think he's worth the accommodation.
Additionally, I am not sure that I am watching the same LeBron that people are accusing of being egocentric and selfish. LeBron literally played with a cast about a strong as a high level rec league championship contender and people tend to forget that. The game has evolved to the point that teams can shoot themselves out of bad spots (see: Steph) and carrying a dead weight team is a nearly impossible task for any individual. That said, we have the players to put around LeBron to really set it off and give GSW a true problem.
If I had to choose, I'd go with LeBron, but I don't truly see this happening.