I like using Pet Botanics which I buy on Amazon as "regular everyday training treats." I like to carry those around in my pockets. They're dry, small, and kind of smelly so the dog really likes them. They come in a variety of flavors, so I switch them up often. As a higher value treat that gets used for recall and more difficult behaviors, such as ignoring other dogs on walks, I use these chicken jerky or steak jerky things by Top Chews that I buy at Costco. I just rip them up into little bits as I feed them to the dog. They're also smelly, and the dog loves them.
I also like to use hot dogs and cheese and human food, but my issue with that is its kind of annoying to stick in pockets and take on walks. If you forget them in pockets, they rot. They're annoying to get out in cold weather because "juicy" things freeze together, and gloves. They spill and get pockets dirty, and if you have a food pouch, which I do, it gets that messy so then you have to wash it every time. And also I hate spending time cutting them up, lol. Lifestyle choice issues, but that's why I like to use store bought treats. If I know I'm going to be working on something more difficult and new to Ralphie, I might dig out some hot dogs to take with me, but typically they're reserved for learning new behaviors at home.
But, some awesome human food type treats I like are the cheese filled hotdogs. Super top notch! Lunch meat. Also, a cheap trick I learned was putting regular kibble in with hot dogs or other yummy meat, and then the kibble kind of soaks up the juices and the flavor.