I agree with Mark that there is something quite odd about the three boats you are comparing. As he says, if a Tartan 37 is in your price range the Catalina 34 seems an odd comparison unless there is something else going on.
A shoal keel is a wasted boat.
A deep fin keel will offer better sailing performance in deep open water, while a shoal keel will offer greater access near shore.
I don't entirely agree with either Mark or Arcb. I would say "it all depends."
There are a number of ways to reduce the draft of a boat during design. All have their drawbacks. The drawbacks get more significant as draft is reduced more aggressively. Bob Johnson has pushed the envelope pretty far with his three-digit Island Packets, for example. For his target market they are great boats; as sailing craft they are somewhat mediocre. A conservative Scheel keel (which is a kind of shoal keel, note capitalization as Scheel is someone's name) is somewhat more expensive but has trivial impact on sailing performance. Then there are wing keels which are too disturbingly similar to anchors for my taste, centerboards, daggerboards, and lifting keels which come with additional moving parts and therefore maintenance.
Once the boat is built you get what you have unless you have very deep pockets.
Some boats are so close in performance that you can't tell the difference. I can think of one hull in particular where the 7' fin and 6' Scheel keel have identical polars. On another with fin, centerboard, and wing options the polar charts look like completely different boats. Sweeping generalizations that are accurate are hard to come by.
I do disagree with
on two points.
First, in shallow water most boaters slow down (an HR54 in Orust being an exception that sticks with me). A boat that can't take a grounding regardless of keel, especially in the cruising grounds you list, has other problems.
With respect to shallow cruising grounds the biggest difference between a deep draft boat and a shallow draft boat is how close to shore you are when run aground. I've sailed my boat with 6' draft throughout the Chesapeake, along most of the ICW, and all over the Bahamas. Sure I've run aground.
I've delivered 7' draft boats to the Bahamas and sailed the Chesapeake with 9'. On the other hand I've had to grind a 5' draft boat into her slip with sheet winches. It's all about care and planning. Again, generalizations are poor substitutes for thought. I would not turn my nose up at a deeper draft boat just because it is deeper than some arbitrary number if the boat spoke to me.
A great deal depends on the cruising ground. The HR54 above hit a rock at 9 kts. People went to hospital. Running Tide (a famous Chesapeake racer) hit a rock at nearly 12 if I recall correctly. For the cruising grounds you describe, grounding in mud or sand is more embarrassing than anything else. There is no excuse for damage to a well-built boat.