Keypad for my new Samsung Smartthings setup?

There are lots of keypads available, ZigBee, Z-Wave etc. Each keypad is a little unique in terms of what features it has (built in sirens, motion sensors, panic buttons etc). The SmartApps you want to use with the keypad must be build to support keypads and also depends a little again on what you’re trying to do with the keypad.

Here’s a short write up on the different types of ZigBee keypads and their features:

If you’re looking at Z-Wave keypads, then Popp is the only full keypad option in the market (EU markets) right now.
There some mini keypads available like the Zipato which has only 4 keys v/s the 10 keys on a full keypad. So if you’re looking do something on your keychain or portable it would be a nice option to check out.

You can check out the first post here for some ideas on what you can do with your keypad (e.g. controlling garage doors, using it for Classic SHM, using it for Patio doors, trigger custom actions etc). It also has links to where you can buy keypads to put them around your house.
E.g. you could install one for each garage door, another one for arming/disarming SHM, one installed as an secondary keypad lock your door lock etc.