If you try to compare the two, albeit not really fair, TBC is probably the better movie. 1242 at its time was just insane (i still remember the premier for that shit in seattle). The soundtrack was killer as well as some of the skiing, Peps segment in particular was ages ahead of its time, with tanner, jon, philou, jf, jp killing it. But, the little big mountain segment in the middle really acts like a big sore because it was largely recycled footage. While it may have been faster big mtn action, it was largely forgettable, except that the movie could have been considerably more had it had true big mountain filmed explicitly for the movie.
TBC was great because once again music was great, the cohesion was nice, content was nice though. (although with its little pitfalls too), the blending of segments was excellent, and some absolutely amazing segments (or just really well made ones) emerged, as well as a unique and strange intro that really sets it apart from other ski flicks.
Even though I'm not a big ski movie fan these days, both movies kick ass, but TBC has a quality, while largely intangible, puts it above 1242.