I think 53/39, 52/36 and 50/34 are pretty much the standard trio that most bikes should be able to handle any of them without requiring additional modifiers to the FD, such as FD extenders and the like.
That said, I think changing the cassette (e.g. to a 11-34) would provide a bigger impact, though that may require changing to a long cage derailleur and a longer chain. Or ideally, change both.
