Intex Sand or Cartridge filter for small pool?

Been looking at some options online and am considering either an Intex Cartridge Filter or an Intex Sand Filter (I think both can come with a built in pump...).

I would need a new in wall skimmer too. Any recommendations welcome...?

Also, I would like to get a Hot Splash air source heater and SWG in the near future. Do I need to consider this when buying a pump included with the filter? (for adequate power...)

Thank you in advance!!
 
Thanks for your reply :)

Pool is 12ft x 3ft (round). I'm not sure about the whole filter/pump set up. I don't want to buy something that's good for the size of pool I have only to find it not good enough if I want to add a SWG and/or heater a bit later.