I guess the answer is in the itineraries and sailing dates in Europe. Check the detailed Queen Mary 2 itinerary schedule
, the Queen Elizabeth itinerary schedule
and the Queen Victoria itinerary schedule
- all with prices, so you can compare rates by month (cruise date).
For Europe I guess the other queens are better options than QM2, since QM offers predominantly TA crossings, and is more expensive. But Mary is the biggest - that's for sure!