If we fly into orlando international I know we could rent a car there and drive to the resort
another option would be to to the disney magical express and then rent a car from nearby or in disney itself?
Which do you think would work better?
I think that is the best idea, especially if you plan on doing more than driving to the resort and parking. If you were just looking for transport to and from the airport, DME is fine.
If you want to do anything else at all, outside of WDW, you really are better off with your own car. I know you can take a cab anywhere you please, but that feels very limiting to me.