That is sort of a loaded question, but if I were to chose, I would have to narrow it down to Utah, Colorado, and Arizona.  Of course, I cannot rule out Nevada, as it has produced some real studs.

But, if I were to start applying for tags with true trophy potential, I would try SE Utah, the middle of Colorado, or northern AZ.

I did here that colorado was a great state for producing some really big mule deer, but was unsure. Thanks

As a statewide average, Colorado kills the lowest percentage of their total bucks, leaving more to grow a little older.  Very few units kill more than 30% of their bucks per year, you can't say that about any other state.  While many states have a few great trophy units, as a whole, you can't beat Colorado.  Oh, and Colorado has higher mule deer densities than most other states.

Any idea of why CO kills the lowest percentage of their bucks?  How hard is it to draw CO and is there a lot of public land to do a DIY hunt?

Ex, where would you reccomend to do a DIY mule deer hunt to get not necessarily a tropy, but a nice representataive mature deer?

I gotta go with Colorado and Wyoming.  I have seen moster bucks in both states.  But I think Utah and New Mexico would be not far behind.  What about Montana??

I think ex is right on with that statement. The other big mule deer states have certain locales that rival any place in the world for mule deer hunting but if you have to choose an entire state, than I think that Colorado is a good bet. If you have the financial means than I think applying for the really good tags in the other states every year is a really good idea. And while you wait to draw one of those really coveted tags in one of the other states you can come to colorado and try and find yourself a good buck on easier to draw tags. So to sum up: Colorado as a whole is the best state but I don't think we have the best destinations for mule deer.

Hawkeye, I asked Ex this question, but maybe you know the answer. 

Any idea of why CO kills the lowest percentage of their bucks?  How hard is it to draw CO and is there a lot of public land to do a DIY hunt?

Thanks.

For starters, there's no general tag.  We've got huge numbers of mule deer, our management goals are set quite high for buck:doe ratios, and for whatever reason, the managers don't mind running the ratios much higher than their objective.  And we have short seasons here and very limited rut hunting with a rifle.