I own a 19ft Glastron, open bow. At the time of purchase, I wasn't diving, so that wasn't a factor in the purchase. It was more for waterskiing etc. I really can't dive with it as Al or steel tanks don't mix well with fiberglass. The fiberglass will always lose out. Sort of obvious. My ladder is great for swimmers etc, but loaded down with scuba gear, drysuit, weights tanks, I'd never be able to get back into the boat with the current , crappy ( for diving ) ladder . If this was strictly for diving, my criteria would be a metal hull, good open stern platform ( able to close off if necessary ), great wide ladder with hand holds a necessity, bench seating along each side with room for tanks and gearing up, you know the routine.
I'm currently looking at the inflatable types of boats. I don't know your needs or where you'll be using it, but look into these also. Stable as hell, just roll entry into the water, ( don't get caught on an attached line ) room to gear up, cheap compared to other types of boats, little storage and transportation costs, no moorage fees, just trailer it. I'm looking at inland lakes for my usage, that may not be yours. Google Canadian Seabright for info. I don't own one but testimonials appear to be good.
16' $2500.00 and that's Canadian dollars Eh! + outboard motor would add to this price.
An add - on: I have seen ladders advertised that you can buy for inflatables