I have both a 3.0 and a 3.2 in a manual transmission car, it might be just me, but I don't sense a difference. But full disclosure, the 3.2 car has an aluminum flywheel, so the driving experience is quite different, especially the initial pull away from a full stop.
I would not rule out a 3.0 because it is smaller in displacement. Nor, would I rule out a 3.2, if that is what my parts bin favoured.
I have never heard that one engine is more reliable than the other, so that is not an issue.
If your car is a 3.0 now, I would stick with a 3.0 as a replacement. Too many parts are different between the 2 engines, right down to the exhaust manifolds.