Hi. The cute white japanese PC-Engine with all the japanese with it's coolest cartridge by far credit card sized cartridges. Though, that's for alone playing (the multi tap will ruin the compactness for two players).
For, with a beautiful loved one, its Neo Geo AES (better if arcade MVS), cartridged based is best and two robust arcade sticks:-)
Though, since the Nintendo NX is going to be cartridged based they say (probably using some contactless tech, instead of the usual teeth that gets dirty), it's probably that ultimately coz' one needs to play in high resolution monitor, perhaps VR and cool graphics, Nintendo having the most exclusives:-)
God bless, Rev. 21:4