My opinion on the second design with the cone.
I thin the cone is going to be difficult to mill, when our machinist was trying to mill the cone for our water block called squirrel, he had to stop in the middle of the process cause he thought that the pin was moving while being milled. But that would be a very nice thing to have inside a waterblock
another thing, just try to at least round the corners marked in red in the following picture. They cause cause some breakage of water flow.