Alex

There are different layers to learning. (See here for an into to this idea and links to more info.)

I am presuming you are referring to e-learning as online video/text modules, and noyt online facilitated sessions with trainers avialable and chatting.

Online in isolated, independent, linear learning.  It's probably less effective than reading a book.  As a result it's probably only a good channel for delivering basic, simple messages.  The training industry might want to tell you something different becasue they are selling sometning, and e-learning is cheaper to deliver.  I expect one day I'll be selling stuff via that channel also.

What you get out of a classroom is a much richer experience.  You not only recieve information from a teacher and their resources, but you discuss and and given space to reflect as you go, often through excecises.

In my opinion the best thing about face to face sessions is the ability to discuss experiences.

That only works if your students are the type to open up and talk.  And if they aren't then it's part of yur job to encourage the discussion along.

I am presuming you are asking the question based on a desire to package up some of your knowledge and pass it on.  The face to face will be more personally rewarding, and more expensive per session.  Online modules can reacha  wider audience but should be focused on simpler skill based topics.