If you are looking at making sausage and pepperoni your better question may be what kind of equipment do I need to make sausage and pepperoni. I believe pepperoni is a fermented sausage so you'll need a temperature and humidity controlled curing chamber. Non-fermented stuffed sausages still require a grinder and a stuffer. Most of these products need a cool or cold smoke at least in the beginning of the cooking process. Cold smoke can be generated without a smoker.
Deciding on a smoker involves deciding how "hands off" you want to be (electric), price considerations (ECB to largest reverse flows), how much cook space you need (small off-sets vs smokehouse).
There are a lot of discussions on the forums about why some people go with electric vs propane vs small offset vs bullet smokers vs large wood fueled smokers.
We can answer any questions you have but what smoker is really broad.