my vote goes for Viva Decor modelling cream. Excellent product. Works fabulously with stencils. One thing though...have warm water in a plastic dish close by to put your stencil into when done. Otherwise the modelling cream will harden quickly and it will make the stencil much harder to use the next time. Dreamweaver's embossing paste is virtually the same as Viva Decor. Dreamweaver does have a wonderful transluscent as well as crackle finish offering that Viva Decor does not have. Viva Decor has probably 12-14 colours available. There is a wonderful selection of pastel colours. Dreamweaver has I think 6 to 8.
One fun thing to do with Viva Decor (haven't tried this technique with Dreamweaver) is to lay a fairly thick coat on your c/s and using your embossing heat gun, dry the paste with it. It will bubble up and give you some really neat texture to work with. Just don't overheat... it will scorch.
One note about 3D stamp paint from Viva Decor.. while it is an amazing product and has fabulous colours it is not raised like Viva Decor or Dreamweaver's. The 3D means the shimmers or glitters in the paints give it the appearance of dimension. If you want your stencil raised from the paper to give a true 3D effect, then go with the modelling cream or Dreamweaver embossing paste. hth