Bumble bee, easily. He is sentient and can transform into basically anything. That is an easy win over Kit and the Batmobile, no more discussion needs to be had.
The time travel thing is kind of hard to argue, but depending on how you resolve the time travel paradox, it's either useless or a good way to break the universe...so it's really actually moot technology. No matter what though I'm going to vote for sentient space alien transformer tech over a moot flux capacitor.