I use iMessage,WhatsApp and the Facebook Messenger app.I do use Hangouts to but more so for video chat then as a substitute for texting. Don't know anyone who has a Blackberry or uses the BBM app but it's handy to have there.
On my mobile I use normal texting as my standard way of messaging but I have friends who don't live in the UK so for them I use Kik which is a great alternative. On my laptop I mainly use skype for calls but when I'm in a group with lots of people I find it better and much more fun to be in a google hangout for video calls.