The main benefit of using USB, is it removes the uncertaintity of LPT ports, and is generally easier to set-up, however they do have some limitations (for the more popular interfaces, they mostly relate to lesser used features that won't affect the majority of users)

You can always go for LPT, then change later, as most Mach compatible USB interfaces can interface to LPT breakout boards.
There are also ethernet based interfaces to consider.