The big challenge using MEAN over LAMP will be deployment.

Time to setup + manage MEAN stacks will likely be considerably longer.

Also, you'll have to write all your code.

Whereas with LAMP, you can do a WordPress setup in a few minutes.

A better question to consider is what project(s) you'll be implementing using your stack.

For example, trying to duplicate WordPress on a MEAN stack... well... requires you write your own WordPress equivalent or find an equivalent.

Start with your application/project + then determine you best runtime environment/stack.