When are you going? I go further north in the summer. Germany in September is ideal, lots of festivals, cheaper airfare and relatively small crowds.
Italy can be miserably hot in the summer, not so bad up north, but beautiful in late fall. If you go in October, you will enjoy nice weather, lower prices (for plane tickets and lodging), and smaller crowds (though some places are always crowded).
Another factor to help you choose is how you like to travel.
Germany is clean, tidy, on-time, and efficient. Train tickets are easy to book and virtually always on time. You rarely have a problem but if you do, Germans fix it quickly and efficiently. In many ways, the downside of traveling in Germany is that there are too many similarities to the US, in terms of customer expectations for service, cleanliness, and reliability.
Italy is completely different. I call it "come what may" travel. The first thing you will notice (though all of these get worse the further south you go) is how dirty things are compared to northern Europe. A clean public toilet is rare. The customer is not necessarily right and customer service is as likely to ignore your problem as solve it. The room or ticket reservation you booked may or may not work out. Your room might not have towels for everyone in your group. If you eat in tourist sections, be prepared for something less than special - at the same price you would pay for better food elsewhere. The most common response by an Italian to a complaint is a shrug of the shoulders. If you can laugh about it, it's actually kind of entertaining. If that bothers you, however, you may not enjoy Italy at all.
