Which is better? that is really a matter of preference as others have said. Down deep in the nuts and bolts I think the actual technology and capabilities of one is much better than the other, but for practical use it doesn't really matter.
As others have said it is probably best to choose the system that operates the brand you already have, or are most likely to purchase, but you should plan on investing in both systems at some point.
As for an actual plus or minus, if you already have a layout together and want to know it will work without any re-wiring, Legacy is the right choice to start, but if you are building from scratch wire it for the 'star' wiring from the start, whichever system you choose, and you won't have problems if you decide to add the other.
I had a couple threads going a while back to determine what there was that one system could do that the other could not and found that they each have a few system specific functions, so for those you'll have to decide which are more important to you. I never got much information about how often people ever actually used some of those functions, other than that the legacy quelling whistle is very popular.
JGL
