Debate fuels my Fire
I'm a new player! Definitely LOVE this edition. Seriously, when hearing things like how armor class used to be calculated, I wonder how people could ever play something else.I'm not a new player so maybe those comments have less of an impact on me. I don't think the mechanics back up your fears, but my fears and experience are not yours so I see things differently I;m sure.
So what your afraid of is magic vs martial balance? It is not an issue for my group as we have very little magic, but this has definitely been discussed before. From a DPR perspective they classes are pretty balanced. So I assume the issue you see is one or both of the following:
I definitely think there can be imbalances, but it has less to do with classes and more to do with player styles. I have three players in my group who are pretty casual (D&D is just a small piece of their headspace) and another two where they try to powergame. The difference in their abilities is wide, and has nothing to do with class but entirely to do with how much research they've done when choosing their various subclasses, spells, feats, etc.