Go with a Tungsten Carbide ring over titanium. Ti rings end up looking scratched up over time, and have to be polished, my Tungsten ring I just buff with a cloth on occasion. (The tungsten carbide ring is also pretty heavy, which I think is cool). Just don't get a no-name tungsten ring. They don't put in carbon, or use copper instead, etc, which looks like crap after time. Neither Titanium or Tungsten Carbide rings can be resized or reshaped, but several of the Tungsten Carbide ring makers offer a trade-in deal for up to 2 times if you need a size adjustment.
Either can be removed, but sometimes it ain't too pretty:
http://www.titaniumstyle.com/titaniu...ng_cut-off.htm
The ER at the hospital I work for has cut fingers off at least once due to a Titanium ring they couldn't cut off. The ED nurses kinda freaked out on me for even getting a Tungsten ring.