Functionally you can achieve the same outcome using any one of the main methods of communication - a short email, a black snapchat, a tweet, an SMS and a Facebook post can all achieve the same thing (provided the message is short enough, or you can be bothered to chain them in the case of Twitter/Snapchat).
That said, all the different apps have a very different social context to them - how I meet someone and the intention of what I want to say to them will dictate which medium I will choose. Indeed even the expected response time will be different.
An email is a comparatively formal means of communication - I would expect the longest response time and would typically choose this for someone I either didn't know so well or was opting for a more official tone.
A Facebook message is quite informal so I would opt for this if I met someone under quite casual circumstances and/or I wanted to downplay the nature of my message.
Whatsapp is quite quick and fast to the point so I would use this for the fastest response time.
SMS has started to feel weirdly distant now, given that almost everyone is on alternative mediums, I find SMS to be quite the oddball for communication.
That said, all the different apps have a very different social context to them - how I meet someone and the intention of what I want to say to them will dictate which medium I will choose. Indeed even the expected response time will be different.
An email is a comparatively formal means of communication - I would expect the longest response time and would typically choose this for someone I either didn't know so well or was opting for a more official tone.
A Facebook message is quite informal so I would opt for this if I met someone under quite casual circumstances and/or I wanted to downplay the nature of my message.
Whatsapp is quite quick and fast to the point so I would use this for the fastest response time.
SMS has started to feel weirdly distant now, given that almost everyone is on alternative mediums, I find SMS to be quite the oddball for communication.
YMMV these are just my personal findings...