As you know we have different kind of nails. For some girls the top of the natural nail is more problematic because of the oil balance in our nail.
Personally I use DN Nail Prep because it doesn't have acid and for me works great.
For the girls who has problem with gel or acrylic building I would recommend DN primer 3in1.
"Extra Strength Nail Primer should be used lightly on buffed surface and let to dry. Used for gel nails and acrylic nails. Has acid content. Strongly recommended for problemmatic nails. "