Before I bought some stepper motors I did some research. It didn't take long to discover that companies like Allegro know more about driving stepper motors than I will ever know so I decided to use an A4988 chip. Then I did a bit more research and discovered it would be a lot simpler still to buy a ready-made stepper motor driver board from Pololu.
Driving stepper motors with H-bridges is like eating spaghetti with a single chopstick.
...R