I am in a dilemma over deciding user favored way of displaying unread messages count, currently, there are two ways in my mind, like Facebook Messenger and like Instagram, Whatsapp, and lots of other applications.
So how Facebook messenger does this is, it shows you how many unread chats you have rather than actual messages, so if Bob sent you two messages, and Alice sent you 1, all of which you haven't read, Messenger would display that you have 2 unread messages (badge over the chat icon in tab bar), to be honest, I prefer this way, avoids the clutter of not knowing how many messages are form distinct chats, it's more informal in short.
But what surprised me is the fact that lots of other very well-established applications such as Instagram and Whatsapp which are very chat-centered, use nondistinct unread messages, so if Bob sent you 5 messages and Alice 2 you would be shown 7 unread messages. And the thing that surprises me more is that all of these three apps are made by one company and have to be based on some research which might show that as much as I prefer the first approach, lots of users do not, I want to ask is there one that I can rely on to make a decision? or do you have any opinion on it? I do not have lots of experience with UX.