I'm not familiar with Fierce, but Acqua di Gio and Halston Unbound for Men are very similar. Do a search for both, and I think you will find some threads that will help you answer your questions. Personally, I like the Unbound, and it can be had for cheap if you're willing to look a bit. Mine was $8.
I have also heard comparisons between Cool Water and Creed's Green Irish Tweed, although I have yet to purchase any Creed fragrances. Hope this helps!