I use a Canon S9000. I have settled on the paper from Micro Mark. It has improved a lot in the past few years and I get really great decals.

White or very light decals can be a challenge.  Because the entire sheet is white, you need to ordinarily trim very carefully to the outline of the decal. I set the background color to the color of the finish on the model in the area the decal will be applied to. I still try to trim closely, but I do not need to be perfect that way.

BTW, I overcoat with Testors dull or gloss coat. I apply two coats.  The first is just misted on lightly.  Too heavy a coat will make the inks run.  Once it has a misted on coat, the second coat can be heavier.

I know it's been a month since this was originally posted, but I use an Epson CX4800 inkjet.  I love Epson's color-brite ink.  Very vivid colors that are archive quality (don't fade or bleed).

I've used Testors' decal system (paper and bonder spray) and have had really good results.  I recently switched to Micro-Mark's paper, but haven't used it yet (hope to, in the next few days).

-Fred