Well, I didn't use mobile app of Lync, but the Skype one is really nice!
Usually, I use it abroad, when I don't want to pay for roaming and I want to call my family with seeing their faces. Way more practical than for example Facebook messenger.
I used an only desktop version of Lync and I must say, that when it comes to professional reasons, I like that app better. It's simpler, less colorful and "fancy". In my opinion, Lync is the best choice for big corporations, when it comes to messaging apps.