All of the above are good options - with their own advantages and disadvantages.
Of the 2 you asked about, I would recommend the paver stones.
They're likely to last longer, and probably look better (IMO).
If you do go with paver stones, make sure to get enough for a walkway to the spa (and I like a small one to open the cover with). Besides looking good, this will help keep mud, sand, etc. out of your new spa.