The first time we did obedience, I used Bil-Jac liver treats.
This time, I have used a combination (they recommended a variety LOL). Old Mother Hubbard makes these super-chickeny flavored training treats (they are small, hard, and round). I have also used mozzerella cheese and yogurt drops or yogurt treats. The yogurt treats smell really good. LOL. They are sold at Petsmart with the other treats. Additionally, I have used some kibble--the pet store guy had given me samples of California Natural. Tae is very food-motivated and, since that's not her normal kibble, it is a bit more "exciting," so I use it, too.