Youll be fine with either of those... Decide what you want out of your board.
The 146 is going to ride higher in the water as already said. That means youll get the same buoyancy out of the board at maybe a half MPH slower, which could make for a slightly meatier wake and slightly less painful crashes. But the downside is that the board will be heavier and tougher to bring around on spins.
The 142 is going to be easier to throw around, however youll need to ride a little faster to get on top of the water the same way, meaning narrower, shallower wakes (very slightly) and potentially more painful crashes.
Personally, I ride 143-144, being 6' at 225. I dont have much problem riding my brothers 139, but I def have to ride a little faster.