Florida, with Pennsylvania as a close second choice.
If the Democrat won Florida, it almost certainly means they won the election.
If the Republican won Florida, it means there's about a 75% chance they won the election. The last time they won Florida but lost the election was 1992. Since 1996, the winner of the election has been whoever won Florida. For the last two decades it has proven the most reliable bellwether.
If the Democrat won Pennsylvania, it doesn't necessarily mean they won the election, 2000 and 2004 being prime examples.
If the Republican won Pennsylvania, they have almost certainly won the election. The last time a Republican won Pennsylvania and lost the election was 1948.
That's a pretty comprehensive and accurate take.
Poll
