Don't get anything with a hub motor, get mid mounted.
2 reasons for this;
1/ The more central and low you get the weight the better the handling
2/ Hub motors are a pain in the arse if you have to take the wheel out to fix a flat.
For the drive units, Shimano are about the best on the market at the moment, Bosch a close second place.
Buy in Europe and plan on selling before leaving as you won't be able to take the batteries on any aircraft.
Or maybe take a bike with you and buy new batteries over there (expensive option).
And finally, plan on getting some really good locks!