154 is a division where there is little talent so i think he could take a belt there and then fight pbf after,more hype.
It's an easy choice for Pac. He can try to win a title at 154(Spinks would be the only champ that he should even think of fighting). However, it's a much smaller payday, the fight may be boring, and he may lose. Or, he could fight the much more important fight against Mayweather. It's a much bigger payday for Pac as well. However, he will almost assuredly lose to Mayweather and he might get embarrased. I say take the money and the loss. There's no shame to losing to Mayweather.
legacy wise an 8th title in 8 divisions is better....but in most boxing fans perspectives fighting mayweather is more important...