You could use Computer, but first I would determine what you want to track about the tablets:

• Are you tracking financial and contractual information? If so, then you want to associate an Asset Class to the Model Category you decide on. You can likely just use Hardware [alm_hardware].
• Is there special information you want to track from an operational standpoint about tablets that varies from what is available to Computers? If so, then you could extend Hardware [cmdb_ci_hardware] or Computer [cmdb_ci_computer] to support this. Then you would need to create a custom Model category to make a connection between the new CI Class and the Hardware Asset Class.
• If the only thing you want to do here is to identify tablets, I recommend a Form factor field on the Model record that you can use to track and report on this. Then you can just use Computer CI Class and Model category.