Nobody has mentioned John Pennekamp State Park yet.
https://www.floridastateparks.org/parks-and-trails/john-pennekamp-coral-reef-state-park
The park facilities are fine, but if you are a diver or snorkler, the underwater environment is absolutely stunning. You really shouldn't miss this,
Islamorada is your best bet. Marathon is a bit rough around the edges, key west is a tourist trap, Key Largo gets pounded by Cubans outta Miami with hand lines keeping hand sized snapper. June is the month to go. John Gargan at whale harbor marina is a 35 yr guide there 3053932714.
Bud n marys is a tourist trap, you better come with a wad of cash or those stanciak clowns wont even look at you. I wouldnt pay them a single dollar of my hard earned money, take your business somewhere elseJohn Gargan is close to the last captain I'd recommend. Being there 35 years has taught him one thing... He's a master of the boat ride and his single screw sled should be added to the reef.
Basically just stay away from Whale Harbor.. There's a few guys there like Benny Spaulding on the Play Baby or maybe Kay K but if you're serious about catching fish w some of the best crews then pick a boat at Bud n Mary's. Don't believe me spend some time down there and go to Post Card Marina, Whale Harbor, and Bud n Mary's and you'll quickly grasp the difference.