Drive through Aiken and you will see both, often on the same street. Pine straw is the regional default, hardwood mulch is the national one, and neither is simply better — they fail in different ways and in different places.
Pine straw wins on slopes. The needles knit together into a mat that stays put, where hardwood mulch floats and washes to the bottom of the bed every time we get a real downpour. If you have a bank, a berm or a bed that drains across itself, straw is the practical answer regardless of what you like the look of.
Pine straw also suits the plants a lot of us already have. Azaleas, camellias, hollies and blueberries all prefer slightly acidic soil, and straw is naturally a better neighbor for them than fresh hardwood. Under established pines it is the obvious choice for the simple reason that it is already what is falling there.
Hardwood mulch wins on longevity and weed suppression. Straw packs down and fades within a season and really wants refreshing twice a year; a good hardwood mulch laid at three inches will hold its color and its weed barrier for most of a year. If the bed is flat, visible from the street and you would rather deal with it once, mulch is less work over time.
What matters more than either choice is how it goes down. Laid over existing weeds, both are decoration. Piled against trunks, both cause rot and eventually girdle young trees. Spread at one inch, neither suppresses anything. The job is weeding first, a cut edge that holds the line, three inches of depth, and the material pulled back off every trunk and stem.
For what it is worth, most of our clients end up running both: straw on the slopes and under the pines, hardwood mulch on the flat beds near the front door. There is no rule saying a property has to pick one.