Both have shocking play-off records. If it was to be one of these two i'd opt for Preston. Purely on the basis that their manager(can't remember his name) got Huddersfield up a few seasons ago in the League One play-offs. Ironically against Sheffield United.
I still have problems with their fans psychosis over them being "robbed" when we finished far more than 9 points ahead when they got deducted 9 points... every one of them acted as if we went up instead of them.