If your Europe trip touches 3 or more countries, the right answer is almost always: one regional Europe plan, not three country plans.
Regional Europe plan
Covers 33 countries on one eSIM. Average per-GB cost beats single-country plans the moment you cross the second border. No re-install when you cross from France into Germany.
When country plans still win
Spending 7+ days in one country and only that one — Spain or Italy, for example. The single-country plan has more GB for the same money.
Avoid the 'global' plan for Europe
Global plans are convenient if your trip spans continents. For Europe-only itineraries, the regional plan is cheaper per GB and just as smooth.