The clear pots seem to be industry standard for growers, and I've kept plants in them for quite a while without problems. But I always re-pot into vented clay, cedar baskets, or as Anna says, mount onto cork. It probably depends where you'll be growing your orchids for the majority of the year.
Mine need fast drainage, and quick drying of the roots, because of our high humidity and heavy rains in summer. Anna has hers in her greenhouse for probably half the year, or more ?? Also high humidity.
If you have long dry spells, a plastic pot is going to keep your orchid roots a bit more moist for longer which could be good. I don't think it matters whether the pot is clear or opaque.
