What is the most effective way to deliver corporate training?

You could ask one of the participant (after they particioate in the training), to train other group of people.  Doing this would force to focus and concentrate fully on the training subject. You may also mention that they will be evaluated as part of their performance measurement.

I use the ADDIE method for effective delivery of corporate training. 

 four things that I would suggest are below:

First: group your participants into teams because this helps to break the ice.  Then put together a system that rewards your teams for participating. Teams like to compete for prizes and this keeps them engaged with the content.Second: Conduct role-plays around a key-learning concept. This will get the participants out of their seats and during the activities you can see who needs additional coaching.Third: Make sure you provide your learners the WIIFM for everything you do. (What is in it for me) Some New Hires feel training is a vacation and do not take it seriously. So if you can tie the content to their bonus and performance appraisal then they will start to pay attention.Forth: Assign each team a3 to5 min teach back on a concept. This activity allows the learners to demonstrate what they know. However, if a team struggles with the assignment then others in the class will pitch in to help that team discover the answer.

Foremost, make sure that the designed training topic is suited with the need of the target participants. Setting set of objectives must be the basis so as you would the measure the effectiveness of the training program. And when the big day comes, the learning process should be interactive. Meaning, the trainer motivates and drives the participants to engage the entire learning process. The trainer should take note that he's there as not being the expert but to facilitate the inputs from the participants to the overall learning process. Please don't forget to include the training evaluation at the end because it's actually a reliable source for continuous development of the training program.

PS: Come prepared and it's gonna be an amazing learning experience.