The "Hard Formula" in H9 (they come in 3 different hardnesses - H3, H6 and H9) is the best! It looks really natural and stays put. I've fallen asleep with my makeup on, and I still have eyebrows when I wake up. At $20 each, it's a bit pricey, but the pencil is quite long. I've been using the same one - Seal Brown for dark brunettes - for over a year.
I love the Shu Brow Pencil, in the hard formula. I was a brow powder girl until I got this. It has the perfect consistency to create those small strokes to fill in your brows. The only brow pencil that I found that looks as natural as powder.
Though this product is a bit expensive, it's well worth it. For starters, the shell is a resuable metal pen! It's super light and durable though. The lead is great. It's a hard texture so it doesnt give that heavy creamy brow appearance. It gives a nice natural finish and it lasts throughout the day! Even through my workouts (I did a sweat test).