Switch owners - myself included - will tell you the system is "perfect for the train" or "on the go". Only... this Nintendopian vision of public transport awash with citizens all playing at once is a fallacy; a marketing spin that sees no real worth in the real world.
Just like Nintendo's rooftop parties(?), Switch usage in the wild is rarer than an Xbox One exclusive - and this is coming from someone who travels an hour a day by train. I've seen more 3DSs and Vitas in the last few months than I have Switches in a year.
In terms of the systems themselves, the almost A4 sheet-sized Switch/Joy-Con combo makes for a supremely unwieldy piece of kit on packed trains and buses - there's just no way to get around it. Playing a Switch on the move means needing ample elbow room, and that's before you get to "assembling" the system by attaching or removing the Joy-Cons, just to make it fit back into your bag again.
Sony's Vita slips nicely into messenger bags or soft sleeve covers with ease. It's made to replicate the size of an average smartphone, and - best of all - your hands don't get cramped playing for long stretches.