Hangouts is pretty good. Now it doesn't require you to have Google+ account, and (unlike Whatsapp) you don't _need_ to use a phone number that's tied to a telco

Hangouts is pretty good. Now it doesn't require you to have Google+ account, and (unlike Whatsapp) you don't _need_ to use a phone number that's tied to a telco, and it handles multiple accounts pretty well.