If you already have a good supply of various hops, you might as well find a good recipe (HBT has a Recipes section
), buy the fermentables and yeast for that recipe, and use the hops you already have. Kits are great when you don't have or don't want to have an inventory of ingredients sitting around.
AHS kits are virtually sure to make a great beer with the ingredients provided as long as the ferment is clean, strong, and controlled. You can re-brew and tweak the recipe to your liking from there, but it's always advisable to start with the standard recipe for the first go of it.