I have been in 5 different hospitals, three general hospital psych wards, and two psychiatric institutions. As far as being a voluntary admission vs. being committed, I have never seen any difference in where you're placed. I can't say I ever had much to complain about as far as treatment by staff. As a matter of fact, there are times I feel kinda' homesick for the safety and security of being inpatient. It was one of the only places I ever felt I fit in.
I saw on your profile page that you have many of the same issues as me.
One thing I found...unless you express the fact that you are in imminent danger of self harm or worse, many places will refer you to out patient. Don't hold back. Two different times I went in for help, but was embarrassed to fully divulge the depth of my condition. Both times I was given a couple of pills and told to seek help outpatient.

The fact that you are considering going inpatient is a pretty good indicator that that is exactly what would be best for you at this point. Good luck.