Personally I got my undersink filter from hestati. So far so good.

You will just have a water outlet on your table top, hence it will not take up space. As for the maintenance, you will have to change your filter every 1-2 years, quite easy IMO.

The reason why you would invest in a table top water dispenser is when you need the hot water function, and also the convenience that comes with it I guess?

And I would like to dispute on the cost part. The filter that I bought from hestati is definitely cheaper than the usual market table top water dispenser.