I’ve always prefered the upper Key’s diving and usually use Conch Republic. Don’t overlook Key Biscayne Park, great diving, only one operator and probably the only wall dive in the Key’s.
Avoid Looe Key Resort!
Another option is to take the M/V Spree out of KW to the Dry Tortugas, this liveaboard is above Blackbeards but no rooms like Aggressor. It would cost you less than than living ashore, you’ll get more dives and Captain Frank’s briefing is worth the price of admission!