The taste of the dry malt isn't going to particularly tell you what it contributes to a completed beer.
You could brew basic 1-3 gallon SMASH recipes with ONE grain, ONE hop, and the SAME yeast as a control, then modify them JUST by adding a single specialty grain.
That's a true experiment...control all of the variables except for the one that you want to experiment on/know about.
That's really the only difinitive way to do it...
I'd test the following specialty grains: Carmel 10, Carmel 60, Special B, Chocolate Malt, Black Patent, and Roasted Barley.
If you've been brewing long enough, I think you would know the difference between the base malts and what they contribute to a beer: