Great question, and one that I think lots of nurses considering NP programs ponder.
I am currently in an FNP program and debated heavily over this issue as well. My background is critical care nursing, I have my CCRN, and really love what I do. So why FNP?
It was honestly multiple factors. Where I currently live, ACNP's are rarely sought after and within my hospital system, only 2 are on the provider list. I also have yet to see a job posting for an ACNP in my region, where FNP positions are always posted and are in demand. In addition to that, I like the broad education you get doing the FNP route. Although babies and maternal nursing isn't my thing, I'm thankful for the education because it allows me to have a broad practice that an ACNP degree will not. Finally, although an acute setting is fun, it can also be draining, and long term I think a clinical setting is more desirable.
When determining which route is right for you, look at you current location and assess the job market. Additionally, ask yourself where you want to be in 5, 10, or even 20 years. Finally, ask yourself what you like and what you want to do with your degree. If the hospital acute setting is where you think it's at, ACNP is probably right for you. If opening your own practice or working in a clinic sounds fun, the FNP route is probably your best bet.
Now having said all that, after I finish my FNP in 2014, I plan on enrolling right away to get my post masters ACNP, because like many of you I am still torn. I think the versatility of being able to practice in a clinical setting and also manage more acute patients would be very valuable. Opening my own clinic is my dream, but I don't want to abandon the acute setting completely either.