We were in Faial last fall, mid/end september I think. They have a couple of dives that are really really spectacular. Princes Alice Banks withe the Mobulas/Mantas and another Bank ( forgotten the name) with the Bluesharks.
These Banks are far off the coast and either no bottom in sight or at 40m or so.It can be currents. The Coastal Reef dives are ok, but not that interesting.
The Islands are in the middle of the Ocean. So, it might not be possible to go out to the top places every day. If, you are unlucky the waves might be too high for a week or so. So, plan enogh time.
Do not plan 2 dives a day! Rent a car drive around, go to the neighbour island, look at the Vulcanoes, do some whale watching, Landscape photography, go for a hike etc etc
Above all stay flexible for the waves to go down. In order to go out to the Banks. The Azores are a fascinating place and I liked it a lot, but you should do a fair bit of research before booking a trip!
You might have the wrong expectations otherwise.
Nikon D800, Nikon 60, 105, 16-35, Sigma 15, Nauticam D800, Zen 230mm, Subsee +5 & +10, 2*INON Z240