I think those wax sticks work the best. It gives a really good hold. You use a little water and gel to help slick it back but Stick really locks it in. I wear my hair slicked back months at a time and I buy the wax sticks by the case. I use Headwear Waxx Stick.
As far as Gel goes, Scurl moisturizing gel works the absolute best, no flaking or anything. If you're natural the combo of the wax stick and the gel really makes the waves in your hair pop.