Terminal Locations at LAX:

JetBlue: Terminal 5
Alaska: Terminal 6
American: Terminals 4 and 5

All of those terminals are connected (post-security) via underground tunnels. It takes 5-8 minutes to walk, according to the LAX website.



Source (Note: edited to crop out other terminals): https://www.flylax.com/inter-terminal-connections

Choosing American means there's the chance that you won't need to change terminals. But personally, I don't think I'd factor that into the decision-making process unless I had a mobility issue or tons of luggage.