Mostly ziplocs but have recently purchased a foodsaver at Costco for like $80. Both work about equally in a normal pot so I wouldn't invest until you are sure you're committed to the method. Where they are nice is when you get a specific container (Coleman coolers with a hole in the lid are popular) and use racks to hold the pouches in place which makes it easier to keep them submerged and allows you to fit more items in while still having good circulation on all the items. Racks tend to be expensive but there are a few hidden deals out there if you look at replacement racks for the all-in-one systems that include their own vessel. I would definitely stick with the universal ones like the Anova since they allow you to use any size container that is convenient or necessary for the type/amounts of food you are preparing.
LoL