You don't need to add extract extract with either Brewer's Best or AHS kits. I have used both, and they are fine. I'd lean a bit towards AHS, though- first of all, they have super fresh kits. They crush the grain when you order, so it's not sitting around. The Brewer's Best are hit or miss, depending on how long they've been around. Also, AHS is having a sale this weekend! Saturday and Sunday- so you can save some money!
All of the AHS and Brewer's Best kits have good directions, and come with everything you need. The AHS kits have a bigger selection- you can make just about any "clone" you want- they seem to have them all.