Frankfurt or Geneva?

Neither city is on the sea, but Geneva has a real swimming lake right in the centre. You can dive off the jetty at the Bains des Pâquis with the Jet d'Eau in front of you, or spend the afternoon on the lawns and pebbles of Genève-Plage. It is still more lido than beach, and the season is short.

In Frankfurt, swimming means a trip out of town to a gravel-pit lake such as the Langener Waldsee in the southern forest, or an outdoor pool. The Main is for sitting beside, not for getting into.

The two eat about equally well, but in very different styles. Frankfurt's cooking is hearty and informal: tart Apfelwein from stoneware jugs, Handkäs mit Musik in Sachsenhausen taverns and a lunch stop at the Kleinmarkthalle, with cheap global food in the Bahnhofsviertel.

Geneva cooks the French way with a Swiss accent. You get lake perch fillets, fondue in wood-panelled brasseries, local Chasselas and Gamay, and polished fine dining in Carouge and the Old Town, but almost nothing cheap or casual.

The two are about equal for sightseeing, and each needs two or three days, but the interest is different. Frankfurt is a museum city: the Museumsufer lines both banks of the Main, the Städel holds the most important art collection of the two cities, and the rebuilt Römer and Goethe's birthplace sit beneath the tallest skyline in Germany.

Geneva's sights tell the story of Calvin and of international diplomacy. You can climb the towers of St Pierre Cathedral, walk past the Reformation Wall, then visit the Palais des Nations, the Red Cross museum and CERN, which have no equivalent in Frankfurt.

Frankfurt is the livelier city at night. It has a real techno and house heritage shared with Offenbach, bars in the Bahnhofsviertel with plenty of character, and rowdy cider pubs in Alt-Sachsenhausen, although it only properly fills up on Fridays and Saturdays.

The Pâquis district in Geneva plays a similar role to Frankfurt's station area, and the squat-born venues around Jonction keep a small club scene going. Otherwise, evenings mean wine bars in Carouge, drinks are expensive, and the city winds down early.

The difference is one of scale. Frankfurt's highest ground is the Großer Feldberg, a wooded summit of about 880m that you can reach from the centre by public transport, and the country around it stays low and rolling: the quiet forests of the Odenwald, vineyard paths through the Rheingau down to the Rhine Gorge, and long, level rides beside the Main. It is a landscape for a day on foot or by bike, and you need no special kit.

Geneva has proper mountains on every horizon. Mont Blanc, the highest peak in western Europe, shows at the far end of the lake on a clear day, and paragliders launch from limestone cliffs just above the city. In winter the ski slopes and the high Alpine valley of Chamonix are near enough for a day trip by road, and in summer there is rowing on the lake and cycling along the Rhône.

Both are excellent bases for day trips, and Frankfurt has a slight edge because of Germany's high-speed rail network. Heidelberg, the castle-lined Rhine Gorge and Cologne Cathedral are each about an hour away, with Mainz, Wiesbaden and the Rheingau vineyards even closer.

From Geneva, the outings are by lake steamer and across the French border. You can visit Lausanne, Chillon and the Lavaux terraces along the shore, Yvoire and Annecy on the French side, and Gruyères or Bern for a longer day.

With children, the two cities are close, though Frankfurt has a little more aimed at them. It has the dinosaur hall at the Senckenberg, a central zoo, the Palmengarten glasshouses, and a wildlife park and small fairy-tale amusement park in the Taunus.

Geneva has no zoo, aquarium or theme park, but the dioramas at the Natural History Museum, the small animal enclosures at the Bois de la Bâtie and rides on the yellow harbour boats work well with younger children. A day in the mountains fills the gap.

Both have compact centres and transport that works, but Geneva is the simpler of the two. You can walk from the station over the bridges to the Old Town and on to Carouge, the trams run on time, the yellow lake boats are part of the same network, and hotel guests usually travel free.

Frankfurt's integrated system covers far more ground, all the way to the Taunus, Wiesbaden and Mainz, and its airport and main station connect directly to long-distance trains. The cost is a tangle of lines and zones that takes a day to learn.

Geneva is the better shopping city if you have something particular in mind, namely watches and jewellery. The flagship boutiques of the big Swiss watch houses line the Rue du Rhône, and the Old Town chocolatiers and Carouge craft workshops add a more affordable side.

Frankfurt is good for practical shopping. You have the department stores and malls of the Zeil, luxury labels on Goethestraße and independent shops on Berger Straße, with stoneware apple-wine jugs as the souvenir to take home.

The gap here is huge. Frankfurt is costly for a German city, mainly because of hotels during the trade fairs, but its taverns, grills, museum pass and quieter summer weekends can bring it down to moderate.

Geneva is expensive all year at every level, from the hotel room to a glass of wine. Free city museums, free transport for hotel guests and cheap lake lidos help a little, and many budget travellers stay or eat across the border in France.

Frankfurt has the stronger stage. Its opera company is among the most respected in Germany and known for adventurous productions, the Alte Oper hosts the radio symphony orchestra, and a post-war jazz tradition lives on in cellar clubs.

Geneva does well for a city of its size. It has opera and ballet at the Grand Théâtre, the Orchestre de la Suisse Romande in Victoria Hall and concerts in a former pumping station in the Rhône. In summer it has the edge, with open-air concerts at a time when Frankfurt's season goes quiet.

Neither city is built around wellness, and the two are about equal. In Frankfurt, relaxing usually means a short trip out to the spa towns: the thermal baths in Bad Homburg or Wiesbaden's Art Nouveau Kaiser-Friedrich-Therme.

Geneva has its own bathing habit in the city itself. In winter you can take a sauna at the Bains des Pâquis and then plunge into the cold lake, Évian and Divonne are close by, and quiet Sundays make the whole place feel slower.