Get a dogbone style. Make sure it is UL/CSA listed otherwise you won't know how poorly it is made inside. Portable cords and adapters aren't required by code to be listed. CW near us has a shelf full of various adapters that aren't listed. Our adapters are Camco.
Keep the blades on adapters and shore power cords lean and shiny and always turn the power off before plugging in. If you're 30 amps and have a choice of 30 or 50 at a pedestal, it's often better to go for the 50 amps straight away because 30s are often tired and abused in comparison. 50 amp pedestals can also have better voltage due to heavier gauge wiring to them.
FWIW, we also carry a 30 to 30 amp dogbone adapter if we absolutely must plug into a bad pedestal and can't go elsewhere. That way if it overheats and melts, we'll only lose the adapter (hopefully).