We used ABA/VB (Verbal Behavior, which is a distinct variation of ABA) when my son was a preschooler. VB focuses a lot on natural settings, error-proof learning, and verbal language. It worked very well for my son and he "learned how to learn" with this method. It was helpful for me because it follows a steady progression of skills and I was able to track his development with visual graphs. We also mixed in some Floor Time methods.
When DS started kindergarten, he went into a classroom that uses the TEACCH methodology. To keep things consistent between school and home, we switched to using these techniques as well. DS has responded very well to this method. I like the fact that TEACCH respects the culture of autism and emphasizes both teaching functional skills and adapting the environment to meet the needs of the individual with autism.