That is kind of a loaded question.
Generally, in-line engines tend to hold up longer than V engines.
It has to do with the forces on the pistons, rods and crankshaft.
Today's engines though, I see very little difference in longevity between 4, 6 or 8 cylinders.
8 cylinder engines seem to be ran harder, so seem to have more problems.
But, do research on the different brands out there. Some brands to very well compared to others.