Galveston is a huge fishery... you can find plenty of places to fish in October with no crowds. (Summer, both are equally crowded in some of the more popular reefs / areas but not October). Galveston is a better fishery and can handle more pressure, the size of the trout are on average the best on the coast, redfish population is growing and doing very well. Sure..Baffin Bay and Big Lake have more bigger trout, but for best average size... can't beat Galveston.
Now, if you want to fish clear grass flats for reds, Galveston has that too, but not as much as port A or other Laguna Madre locations. it really just depends on what you want in a trip.
Galveston can be off the hook in October. Port A has a better beach, there's plenty nightlife in both locations.