*examine wood grain clarity.
*check the variety of wood offered and the look of the planks. Watch for repeated prominent features, such as knots or distress marks.
*Consider length of warranty and what it covers. Water damage?
*Glue type matters. Waterproof glues help seal out moisture from the wood core.
*How precise is the fit between planks?
*Check the bottom sealer. Resin backed is better than paper.