Go test them out.  All three have demo versions you should be able to download.  Lightwave is probably the cheapest to start with out of the three... but lots in the game and movie industry use the other two.  Interestingly, Maya was bought out by Discreet not long ago, so Maya and Max are really run by the same company soon, which also happens to be the same company that overpriced the heck out of Motionbuilder for us freelancer types once they bought Motionbuilder from Kaydara a couple of years ago.  Max, in my book, has always been way overpriced, but lots of others disagree with that thought.  If you really want cheap though, check out 3d wings or Blender.  Stay away from trueSpace - it's mostly a buggy toy, or at least was up til version 5, when I stopped upgrading mine.

How long it takes to model something is often a function of how familiar you are with the tools and interface, and what features the software incorporates to speed certain processes along. For example, Max has more tools dedicated to architectural modeling than LW does (although LW is trying to catch up).