For us the very best divingboat is a Cat.. There is more than enough room to store equipment, the draft is exceptionally low on most of the boats so you can get as close as you need to the diving areas without fearing running aground. If interested I have a cat out of the water at Salt Creek Marina in St. Peters burg getting outfitted as a dive boat.
If you don't have a sugar scoop on the back of the boat, diving from it is VERY hard. When we tried, we ended up having to take our equipment off in the water and putting it in the dinghy, then rough handling it back into the boat.
On our cat, we just come up the swimstep, take it off in the cockpit, rinse, hang it up, put it away. LOTS easier.