Which one is your favorite in terms of the beauty of the scent, sillage, projection and longevity?
Like Guertlain, it's strong and to the point - a classic vetiver, but I don't find myself wearing it often. It is inexpensive though, and very well regarded as the granddaddy of the vetivers. Lasts and projects nicely, possibly a little strong in the first 15 minutes but then settles down to a much more comfortable level.
Creed OV is light on the vetiver, but of these three it is my favorite, and I wear this one pretty frequently. Not worth the full retail price ($300+) but if you can get it at an online discounter for about $150, it's a fair price for what you get. Lasts 10+ hours and projects nicely as well for at least the first 6+ hours.
Mugler is more soapy and on me at least it didn't last terribly long. When I was testing it a while back, I chose Creed OV as the better scent with much better longevity. It's inexpensive and a decent alternative if Creed is outside of your price range.