Lille or London?

Neither city is a beach destination, and from both it is about an hour by train to a cool northern sea. From Lille you reach the wide, windy sand at Malo-les-Bains near Dunkirk. From London you reach Brighton's pebbles and pier, or the sandier shores of Margate and Whitstable.

London comes out slightly ahead because you can swim without leaving the city. The lidos at Brockwell Park and Parliament Hill and the Hampstead Heath ponds offer a summer swim, and Lille has nothing like them.

Lille's cooking belongs to one region: carbonnade flamande, potjevleesch, the welsh and Maroilles in the estaminets of Vieux-Lille, with beer at the centre of the evening. It is filling and distinctive, but there is little beyond Flemish dishes.

London offers far more choice. There is Bangladeshi curry on Brick Lane, Punjabi food in Southall and Turkish grills in Green Lanes, along with a large fine-dining scene and markets such as Borough. A food-led trip has much more to explore there, though every meal costs more.

Lille has one museum worth the journey on its own, the Palais des Beaux-Arts. Around it are the Flemish baroque of Vieux-Lille, Vauban's citadel and La Piscine in Roubaix, and two or three days do it all justice.

London works on another scale. There are the British Museum, the National Gallery, the V&A and the two Tates, most of them free, and then the Tower, Westminster Abbey and St Paul's. Even a week there leaves plenty unseen, so a trip built around sights and collections is far richer in London.

Lille's evenings are friendly and led by students. There are cheap bars on Rue Masséna and Rue Solférino and quieter beer cafés in the brick cellars of Vieux-Lille. Clubs are few, though, and a really late night has traditionally meant crossing into Belgium.

London offers a much bigger night out, and each district has its own scene. Soho has late cocktail bars and the gay scene, Shoreditch, Hackney and Dalston have clubs and warehouse parties, and Brixton and Peckham have big venues. Many pubs still close early, but the weekend runs long.

Outdoor time around Lille is flat and gentle. There are the Citadel park and the Deûle towpaths for cycling and the low Monts de Flandre for short walks, and the cliffs of Cap Blanc-Nez make a long day out.

London has much more green space close at hand. Richmond Park and its deer, Hampstead Heath with its views over the skyline, and Kew's gardens are all inside the city. The Chilterns and the South Downs are about an hour away by train and have well-marked footpaths.

Both cities are excellent bases, and the difference is where the trains take you. Lille sits on a border crossroads: Brussels is about half an hour away, then come Ghent and Bruges, Paris by TGV, and the First World War battlefields around Ypres, Vimy and the Somme. One stay can take in several countries.

London's day trips stay in England but go deep: Oxford, Cambridge, Windsor, Bath, Stonehenge and Canterbury. Choose London for English history and countryside, and Lille for Belgian cities and a day in Paris.

Lille works for a few days with children. The days centre on the Citadel park's small zoo and playgrounds, the natural history museum and the Forum des Sciences, with Pairi Daiza and Nausicaá as bigger outings.

London has much more for children. The Natural History Museum, the Science Museum and the Young V&A are free, and so are the parks with their playgrounds and boating lakes. Add London Zoo, and Legoland Windsor outside the city. The difficulties are long distances and stairs at many Tube stations, while in Lille the main problem is the cobbles.

Lille's strength is its size. The centre is flat and easy to walk, and both stations sit beside the old town, so arriving and leaving is easy. The automated VAL metro and the tram reach out to Roubaix and Tourcoing.

London's network covers far more. The Underground, the Elizabeth line, the buses and the riverboats reach almost anywhere, all paid with one contactless card. Journeys are longer and the Tube is crowded at rush hour, but the system carries a visitor across a much larger city.

Lille is good for shopping by the standards of a regional city. The chains are on Rue Neuve, the Euralille mall is by the stations and independent shops line Vieux-Lille. Its standout is the Braderie each September, a flea market across the whole city that is worth timing a trip around.

London is one of the great shopping cities. Bond Street has the luxury houses, Oxford Street the flagships and Savile Row its tailors, and there are department stores such as Liberty and Selfridges and markets from Portobello Road to Columbia Road. For a shopping trip it is far ahead of Lille.

Lille is clearly the cheaper city. Hotels are reasonably priced except during the Braderie and the big trade fairs, and estaminet meals, beer, the metro and the museums cost much what they do across urban France.

In London, central hotel rooms are small and cost a great deal, and meals, pub rounds and theatre seats add up quickly. The free national museums and parks help, but a London stay costs much more than a similar one in Lille.

Lille has a solid season for its size, with the Opéra de Lille, the Orchestre National de Lille, the Théâtre du Nord and contemporary dance in Roubaix and Tourcoing. It is worth an evening rather than a trip of its own.

London is a world theatre capital. It has the West End, the National Theatre and the Globe, the Royal Opera House, five major orchestras and the Proms, plus jazz cellars and rock venues. Anyone planning a trip around performances should choose London.

Lille has no bathing tradition of its own. Rest there means a hotel spa or a slow afternoon in a Vieux-Lille tea room, and the nearest real thermal bath is a short train ride away at Saint-Amand-les-Eaux. The city's easygoing pace is its main advantage here.

London has more to offer, even though it is the faster and more crowded city. Its historic public Turkish baths in Bayswater and at Ironmonger Row in Islington have steam rooms and plunge pools under tiled vaults, and the grand hotels of Mayfair and Knightsbridge run full-scale spas. For proper thermal waters, Bath is about an hour and a half away by train.