Which NP is non-limiting to specialize in?

This is somewhat dependant on the state you live in. A FNP has a very broad scope of practice, birth to death and in my state an FNP can practice in specialty areas (I have FNP friends that work just in mental health, obstetrics, pediatrics and ED). However in some states those areas would have to be filled by a psych NP, CNM, peds NP or acute NP. And even in my state there is a push for hospital based NPs to be acute care NPs.

But really don't you think you should look at what you are interested in? For instance psych NPs are very sought after in many areas but jsut because you can get a job as a psych NP does not mean you would be good at it. You have do be doing some thing you enjoy. Usually if you loved being an OB nurse you will enjoy CNM, loved being a psych nurse, will enjoy psych mental health NP, etc.

Good luck.