Sporting Clays by a HUGE margin. Each place is different; most have a course with 12 or more stations, and each station is different.
Trap and skeet are EXACTLY the same, no matter where you are - Maine to Miami, San Diego to Seattle, and all point in between.
In serious competition, you need perfect scores in trap and skeet just to get to the shootoff; whereas in Sporting, the number of perfect scores can be counted on one hand.
So it comes down to this: do you like BORING repetition where the targets are always the same, OR, do you like an extreme variety where each course utilizes its terrain to set challenging and fun targets?