The Undertaker vs. Underfaker match is pretty poor in retrospect, but if you lived during the time it was awesome stuff. Regardless of the match quality, the build was great and I'd say the payoff was fine through the my then 15 year old eyes, though I won't deny I'll never watch it again.
: Also, they didn't really have lower-tier PPV's back then so Summerslam was the most logical place for the payoff.
Now, if we're talking about Summerslam '94, let's not forget that there was also a five-star classic on that card, Bret vs. Owen's cage match, which in my mind remains the best WWE blue cage match ever. Yes, I know some think its overrated, but if someone can please tell me another blue cage match that was better, I'll be glad to debate it with them.