I tried Heat & Bond Featherweight for a lighter appliqué and was very disappointed. Could it have been operator error, maybe but I was very careful.
I would recommend using Wonderunder but "window" your large appliqués. To window you draw the shape on the paper side of the appliqué and then draw another line about 1/4 to 3/8 inside the appliqué shape. Rough cut around the outside line on the Wonderunder and also cut along the inside window line. This gives you an odd shaped Cheerio to fuse down to the back of the fabric. Make sure it is laying nice and flat and fuse the window to the back of the fabric per instructions. After it has cooled you cut out the appliqué following the first pencil line, peel off the paper and fuse the shape down to the background fabric.
I have no experience with Misty fuse or Steam a Seam.