FP4 is a great film. So is Acros. They look pretty different though. I've settled on FP4+ since Plus-X died but I've been shooting some Acros lately and have to say I really like it.
There isn't enough price difference between these films to make that a deciding factor unless you are shooting a LOT of film and, even then, it will probably get swamped in the "noise" of chemical and paper costs.
Acros is AMAZING. I wish they made it in ISO400 too.