The problem here is that there is only one person on this site that can tell you what helmet to do & that person is you...
Every single person who is going to comment on this post is going to have a different answer, because every single person is going to have a favorite helmet. I personally don't like any of them, but that isn't going to help you any. I had a similar issue when I first started my project last year, I couldn't decide between the Locus, The Reach Gungnir & the Halo 3 Master Chief helmets...in the end I didn't choose any of them, I opted instead to do Carter from Reach & now I have a VERY nice Commander helmet. Eventually I'd like to get the others (there's no rule saying you can't have more than one helmet), but I'm happy with the one I have at the moment.
Good luck in making your choice.