Have you done extract before, or are you beginning with AG? The fermentation process and equipment for AG is exactly the same as extract, so you can use whatever you already have if you are already extract brewing.
Buckets/better Bottles, Carboys, or anything else that's food safe and airtight that you can drill a bung hole into. There are pros and cons to each, it pretty much comes down to personal preference that fits into your process.
I have three glass carboys, two better bottles, and three buckets. I find that I use the better bottles and buckets most often, and really only use the glass when I intend to age for a fairly long time. The glass carboys are just too heavy to move around with 5+ gallons of wort in them, so I don't use them all that often.
Primary #1 - Midnight Ryeder (Midnight Wheat and Rye)
Primary #2 - Florida Weiss
Primary #3 - Kane-DOH APA (Honey Citra APA)
Secondary #1 - Downtown Flanders Brown (brewed August 2012)
Keg #1 - Raspberry Florida Weiss
Keg #2 - Cinnamon Raisin Cider
Keg #3 - NONE!
Bottled - NONE!