Well, Like I said above, Micro Sol is what I use. I have also used Micro Set, which is a little more like the Testors stuff. Honestly, I have found MicroScale products to be better, and I use them exclusively now. The MicroSol will make a decal conform to any surface on any model, it is some incredible stuff. MicroSet I use less frequently, but it does a good job to get rid of air bubbles and impefections on a flat smooth surface.
Testors decal solution is about the same; it works the same and probably has some of the same ingredients. The resons I don't use it are simple: 1) I needed something stronger, 2) small quantity for the price, and 3) It has a tendency to corrode the metal top of the container, rendering it useless. I wouldn't call it a bad product, but it doesn't suit my needs.