Aix-en-Provence or Lille?

Neither city is on the coast, but Aix is much closer to water you can swim in. The coves of the Côte Bleue, Cassis and the calanques are all within an hour by car, and the Mediterranean is warm enough for a proper swim in summer, even if the inlets are small and pebbly and fill up in August.

From Lille, the nearest sand is Malo-les-Bains at Dunkirk, a wide, windswept North Sea beach where the water stays cold. It suits a bracing walk, or sand yachting on the Opal Coast, rather than a day of swimming.

Both cities eat well and in a strongly regional style, but the cooking could hardly be more different. Aix is olive oil, goat's cheese, daube and chilled Coteaux d'Aix rosé, with a long terrace lunch as the main event and calissons to finish.

Lille cooks with beer and butter: carbonnade, potjevleesch and Maroilles in wood-panelled estaminets, with Belgian ales instead of wine. In both, the choice beyond local cooking is thin, and the showiest terraces in Aix are selling the view more than the food.

The two are evenly matched here, but they offer different things. In Aix the town itself is the main sight: fountains, plane trees and the honey-coloured mansions of the Mazarin quarter. Cézanne's studio and the Bibemus quarries add a personal thread through one great painter's life.

Lille's strength is one great museum, the Palais des Beaux-Arts with its Flemish masters, surrounded by the Flemish baroque brick and carved stone of Vieux-Lille. La Piscine in Roubaix and the LaM are a metro ride away. Either city fills two or three days.

Lille is the better night out. Thursday nights on Rue Masséna and Rue Solférino are loud and cheap, the brick cellars of Vieux-Lille hold beer and cocktail bars for a calmer evening, and the Belgian clubs are close by.

Aix's students give it more evening life than its size suggests, but people stay on the terraces around Place des Cardeurs, things finish early, and a real club night means going to Marseille.

This is where the two differ most. From Aix, the limestone of Sainte-Victoire is close by for summit trails, and the Calanques offer some of the best coastal walking in the Mediterranean. The Luberon, the Alpilles and the Verdon gorge add cycling, kayaking and canyon hikes. Spring and autumn are the seasons for it, as summer fire risk can close the hills.

Lille sits in flat, farmed Flanders. The Citadel park, the canal towpaths and the low Monts de Flandre make for easy walks and rides, and the chalk cliffs of Cap Blanc-Nez are a long day away.

Both are excellent bases, but for very different journeys. From Lille you go mostly by fast train, often across a border: Brussels, Ghent, Bruges and Paris are each about an hour away or less. On the French side there are Arras, Amiens and the First World War battlefields.

Aix looks to Provence. Marseille, Avignon and Arles cover Roman and papal history, and the Luberon hill villages and the Alpilles cover the countryside. The towns are easy by train, but the villages need a car, while Lille's best outings need none.

Children find more to do inside Lille itself, while in Aix the best family days happen out of town. In Aix itself, younger ones get pedestrian squares, fountains and ice cream. Most families stay somewhere with a pool and drive out to the zoo at La Barben, the coast or the Calanques, and avoid the heat of summer afternoons.

Lille keeps children busy even on rainy days. There are the Citadel park with its small zoo and playgrounds, the natural history museum, and a hands-on science centre reached by metro, with Pairi Daiza and Nausicaá for bigger outings. Pushchairs struggle on the cobbles of Vieux-Lille.

Aix is a pleasure on foot within its old town, but once you look beyond it you will want a car. The TGV station sits out on the plateau, buses barely reach the Luberon villages, and parking in the centre is tight.

Lille needs no car at all. Its two stations are a short walk from the old town, and the automated VAL metro and the tram carry you out to Roubaix and the museums in the suburbs.

Both offer a similar mix of boutiques and markets. In Aix, the lanes around Rue d'Italie hold fashion, delicatessens and homeware, and the souvenirs are distinctly Provençal: calissons, santons, olive wood and printed fabrics.

Lille adds chain-store streets and the Euralille mall to the independent shops of Vieux-Lille. Its big annual event is the Braderie in early September, a flea market that takes over the whole city.

Aix costs noticeably more than Lille. Central hotels are few and mostly boutique, the opera festival fills them in July, and the car you need for the countryside adds to the bill. Market picnics and lunch menus in the back streets soften it.

Lille is the easier city on a budget. Rooms are reasonably priced for most of the year and only climb during the Braderie and the big trade fairs. Estaminet meals and beer are fairly priced, and the metro is cheap.

For most of the year the two are comparable, and each has serious venues. Aix has the Grand Théâtre de Provence and Ballet Preljocaj's home at the Pavillon Noir. Lille has the Opéra de Lille, the Orchestre National de Lille and the Théâtre du Nord, and it is better for rock and pop, with the Zénith and the Aéronef.

What puts Aix ahead is July, when its opera festival fills the courtyard of the Archbishop's Palace and draws the international opera world. Book early, as the main productions sell out.

Aix was founded on its warm springs, and you can still see it. The Thermes Sextius stands on the site of the Roman baths, some fountains run warm, and outside July the town moves at the pace of a long lunch.

Lille has no such tradition, and its famous swimming pool is now an art museum. Rest there means hotel spas and the tea rooms of Vieux-Lille, and the nearest thermal bath is a train ride away at Saint-Amand-les-Eaux.