I was on the fence, and couldn't decide a couple of things finally pushed me over to the sport side of things.
I chose the sport because of the weight, I tried both on and felt it was a good balance, especially when I ran. on trying on the SS, it felt more prone to move around a bit more being heavier.
Price, you're paying a premium for the materials, its the same exact watch.
Gen 1 product, I figured while everything should be fine and work as expected, I wanted to minimize my exposure so I opted for the less expensive model.
External usage, I run a lot and I wanted the increase viewing of the ion glass over the sapphire.
Scratches, the SS will incur scratches, will it be a scratch magnet? Who knows but I didn't want to deal with buffing out the scratches every so often. Am I overblowing this issue, perhaps but when I'm ready to drop 600 dollars for a SS apple watch, the idea of having to deal with scratches did not really make me feel better.
I also opted for shatter resistance (ion glass) vs scratch resistance. I'll throw a zagg screen protector on it and I'll have high scratch resistance.
Overall, this is a personal decision, I gave you my thoughts on why I chose the sport over the SS, but that doesn't mean that's the best for you.