I must admit that I seldom use the Split Stitch as a filling stitch but this wonderful example embroidered by Refabulous. shows it can do the job perfectly!
The filling stitches I most often choose, not taking into account 'semi filling stitches' like the Seed Stitch, are probably the Satin Stitch , the Long and Short Stitch and the Brick Stitch. What's your favourite filling stitch?