So how to figure out what joist hanger is right for the job? Let's simplify the choices a little first. What are we looking for for deck construction?
Face Mount
There are top mount hangers, but we can mostly ignore those. Face mounts are attached right into your beams or ledger. Perfect for the exposed wood of a deck.Z/HDG/SS
That stands for Zinc, Hot Dipped Galvanized, or Stainless Steel. Only hangers somehow protected from the elements should be used. If they are touching any pressure treated lumber, they will corrode even faster. Zinc is the most affordable option. Stainless is the best, but will cost you at least 4 times as much.External or Concealed
External flanges are cheaper, and work for most applications. If your hangers will be visible from outside the deck, consider concealed. Also, if you have end hangers that can't be attached on both sides (like the end joists on a flush mounted deck) they can work.Size it Up
Since your joists are probably 2x lumber, you just have to worry about length. You can go to the Simpson site, they will tell you which sizes will work with your lumber. There is usually a range, a 2x8 hanger can work with a 2x10 joist is it's rated for it.Check Your Loads
This is a little more complicated. This is a chart from Simpson that shows loads for some hangers. It's great to know the loads, but you will need some engineering to understand what you need.
Here is another chart that shows loads with nails rather than screws.
I'll leave the nails and screws for another time.