I am a firm believer is feeding at most waterings at a dilute concentration, and find that 125 ppm N is a good number to shoot for. Dividing 10 by the %N on the label tells you the teaspoons per gallon to use, and if you have to round to make it easier to measure, you'll still be close enough.
A good orchid food is any fertilizer than contains a complete array of ingredients (listed here:
Fertilizers & Plant Nutrition), and is not excessively high in nitrogen (I view a 30-10-10 to be too high). Other than those criteria, I don't think a particular brand is critical, although I do prefer the Dyna-Gro "Grow" formula or the GreenCare Orchid Specials - the original, so-called, "MSU" fertilizers.