Hamburg or Berlin (Germany's first and second cities)
Berlin may be German's capital city - it's not the 1st (most important) which businesswise is Frankfurt am Main. I would also question by what yardstick Hamburg is the 2nd German city - it's certainly the biggest port city, but I would have said that, again, businesswise probably Munich and Stuttgart are more important.
Whatever, even if BER and HAM don't have a network of intercontinental services flown by Lufthansa, they do have a much more comprehensive network of European services - most German airports do - than their UK equivalents. This is because Germany is a federal country, where the states (Laender) are roughly equal in importance, and all the state governments are really interested in growth of, and support for, their economies. To see how federalism works look how Edinburgh airport's scheduled network has grown since it became a "proper" capital city where the Scottish government sits, and wealds real power.
You have to look to France for a country that is similar to the UK, where Paris is all dominant, and hence Lyon, Marseilles, Bordeaux, Toulouse, Strassburg etc don't have proper direct links to many principal cities by the National carrier - who could justifiably be referred to a "Paris Airways". Mind you, even in France their is a proper high speed rail network joining provincial cities to the metropolis - something the UK still doesn't have!