Simple, Fast, better than Whatsapp (my opinion).
It’s a brand new application from Google. Allo.
A clear competitor to WhatsApp if you ask me. It does not allow to make calls, but as you may know Google also as Duo for the purpose (not to mention Hangouts).
It presents as a very fast application not hogging your phone at all. Also from my perspective is much more aligned with present design trends and it fits completely on your Android Operating system.
I strongly advise for you to give it at least a try.