I didn't choose either because each one has its place.
The Ouidad Double Detangler is a GREAT comb for detangling (hence the name) without snagging or pulling the hair. In the end you end up losing less hair while detangling, and it decreases detangling time considerably. I use this when I have a serious detangling job ahead of me, and when I'm waaaaaaayyyyyy into my relaxer stretch, as I was 17 weeks post when I found out about it.
Since I recently got a texlax touch-up, my hair hasn't been tangling as much, so I use my seamless shower comb (Jilbere from Sally's, about $2.99). Unless, as I stated before, my hair is really tangled. Then I break out the Ouidad.
So the seamless shower comb is what I use for the light jobs, and the Ouidad for heavy duty. It's all about using the right tool for the specific job IMO.