Both. Even the Iridium doesn't have full coverage. SSB radios although archaic to some, offer a dimension to your boat's communication not offered by a sat phone. Costs are similar to purchase however sat phones require minutes to be purchased. Sat phones fit into a ditch bag, not the SSB. Internet capabilities come with a sat phone not with the SSB. SSBs can be programmed do HAM functions. Cost for internet is high for the sat phone, Sailmail for the SSB is about $250 per year. WeatherFax is available on both, yet a computer and printer are required. A ships licence and a registered MMSI are required for the SSB, which is a good thing. I'm sure there's more but you can search previous posts.
There are previous posts on this topic as well as multiple threads with as many opinions.