Never played TS, but not a huge fan of WCS. That said, a lot of other people who played mine before I sold it loved it, so it is definitely a popular game.
If you're getting a good buddy price, you must know him well enough to ask to sample the games. Go in a couple times, play only one machine for an hour or so one night, then play only the other on a different night. Get a feel for them and see which you cotton to more. Then take it home with you.