Hi Steve;

IMHO, the best looking, easiest sanding, easiest to match filler is wood glue mixed with sanding powder to a very thick paste. If you mix it thick enough, with a LOT of wood powder, the end result will look like wood. Epoxy + wood powder or anything else is not very easy to work with. You will find that discolorations are easy to come by. Wood + water based wood glue is a dream to work with, just use lots of wood powder.

Water based fillers are never the right color, and I've yet to find a coloring agent that won't bleed when you (i.e.) alcohol wash the surface before glassing . . . Glue and wood powder are there for the duration.

Good Luck, Spidey