You're gonna hear every arguement for and against each one of them.
Certain people will not service an I/O, have problems with them, need to replace parts that are expensive and determine that they aren't cost effective compared to outboards.
Outboard proponents will have the attitude "if it costs too much to fix, I'll just hang another one on the boat".
It all depends on what you want out of a boat and are educated enough (common sence) to handle.
Personally on a boat size under 24' I'd rather have an outboard situation, I'm floorspace greedy and appreciate the room. Several years ago Albemarle came out with a 24' CC and is lovely.
Will never be able to afford one but it's something else. LIST $62,000
Engine is mounted under console, creating the best of most worlds between I/O and outboard.
Besides, there is just something about the smell of 2cycle in the morning. I'm gonna miss it when I run out of older fuel mixed engines, they are gettin harder to find.