I have the hard cover Millenium Star Atlas and it always sees use in the field. Uranometria 2000 has more DSOs but with a stellar limiting mag of 9.75 it has 1/3rd the number of stars in MSA and it might prove inadequete for starhopping to faint DSOs with a 10-12" scope. For that reason, if I had to choose just 1 atlas, I'd go with MSA, besides it still has some 10,000 DSOs which should keep anyone occupied for damn long time!
