I use Keynote (for conference talks) and Powerpoint (for workshops and other slidedecks that I need to share with coworkers).

I prefer Keynote but can wrangle PowerPoint to a get decent slides and it even has some advantages for example control of movies is much better as you can have pause points.

One thing to watch if you go iPad is that iOS and OSX Keynote are not quite the same. Can't quite remember which features are missing but custom fonts is one and there were others last time I tried.

I'd stick with a Mac of some sort and use remote - I've never really like the iPhone as a presenter remote as someone needs to look at the screen, and use a Logitech one.