Stepper motors are wildly popular for many small projects because
it is so easy to control their position, and you don't need an encoder.
See my notes on stepper motors
AC motors come in all sizes and there are many types.
See my notes on AC motors
DC motors are quite simple, just don't burn them out.
Someday I'll write some notes on DC motors
Drop me a line!
Tom's Computer Info / email@example.com