My boys' favorite potty-training treats are Zukes Jerky Naturals, Soft & Chewy Buddy Biscuits, and Natural Balance Tillman's Training Tips. I always break them up into smaller pieces so the bag lasts longer.
I inserted the links so you can see what they are. 
__________________ ♪ Jimi | Marshall | Hendrix ♫ "When the power of love overcomes the love of power, the world shall know peace." - Hendrix |