I/O or OB

[bcurling]

Once again I am intrigued by the dialog with the newbie wpreach, (Welcome onboard wpreach, this is a great forum) regarding the engine. My question is this;
Everything being equal, which is better I/O or OB? Is there some outstanding reason in performance, maintenace, longivity, fuel consumption, etc, that sets one type of engine above the other? I am trying to learn all I can about these boats and their engines. Thanks for sharing your thoughts.