I know that you've got some conflicting views about which is better and also think that, perhaps, the combination of both is what's best. I'd argue that it's very much an individual thing. You could certainly produce a strong speech, with a really strong contention, around this idea that students have individual learning styles and that asking whether ebooks or textbooks is better is too narrow and fails to take into account these different styles. You could then broaden that to a short discussion about flexibility in the classroom, and how this is just one example of how the modern classroom needs to be flexible, giving students the opportunity to use textbooks if they wish, or ebooks if they so wish too.
You could also discuss the potential impact of the cost of ebooks vs textbooks on families from low SES backgrounds. There's a lot to discuss around here. Ebooks themselves are cheaper to purchase, but then there's the question of having the facilities to view ebooks. Do they need a tablet? A computer at home? How do we support families who don't have access to these things? The same could actually be said about textbooks too.
A third option is to decide that we should have neither. You could very reasonably argue that textbooks aren't what they're cracked up to be, and encourage a narrow examination of the course. Examples can be drawn from universities, for instance, that don't really have textbooks (this is partially untrue, but certainly the course isn't taught to the textbooks and it is rarely the case that university students find much use in textbooks). I think it's very reasonable to say that textbooks belong in a bygone era, particularly with the access we have to information via the internet.
I guess in summary what I'm trying to encourage here is to take your analysis to a greater depth. I've just come back from listening to speeches by the best public speakers in Victoria, and what they tend to do better than your average Joe is not just in their speaking, but also in the fact that they push their topics to a more nuanced discussion that challenges people's thinking, rather than making a solid, albeit boring case for something pretty straightforward.