Koh Phangan or Langkawi?

Both islands are built around their beaches and the sea is warm all year, but the swimming is different. Koh Phangan has a ring of separate bays. Thong Nai Pan and Bottle Beach in the north have deep, calm water, and Haad Yao and Haad Salad are dependable for a swim. The long southern shore, though, turns to reef flats at low tide.

Langkawi's beach life is centred on one long, wide strip of pale sand at Pantai Cenang and Pantai Tengah. The water there is shallow and good for paddling, though it is less clear. Tanjung Rhu and Datai Bay are the quieter alternatives. For snorkelling, Phangan has the sandbar out to Koh Ma, while on Langkawi you take a boat to the marine park islands.

On both islands you eat simple, cheap local food, and in neither is eating the reason to go. On Koh Phangan that means Thai curries, som tam and noodle soups, best found at Thong Sala's evening market and Saturday walking street, plus a separate scene of vegan and raw cafés in Srithanu.

Langkawi's cooking is Malay, with a Thai influence along the coast. Its pasar malam night markets move to a different village each evening, and seafood places sell fish and prawns by weight. Duty-free beer and wine turn dinner on Langkawi into a beach evening in a way the Malaysian mainland can't match.

Neither island is a place for sightseeing, and a morning or an afternoon covers the main sights on either. Koh Phangan's heritage is mostly spiritual: Wat Phu Khao Noi, the meditation temple of Wat Khao Tham, and the royal initials carved into the rocks at Than Sadet.

Langkawi has slightly more to make a tour of. There is the legend of Mahsuri, whose tomb sits in a small village of traditional Malay houses, as well as the rice story at Laman Padi and the state gifts in the Galeria Perdana.

Few places anywhere differ as much at night as these two. Every month Koh Phangan packs tens of thousands of people onto Sunrise Beach at Haad Rin for the Full Moon Party, and on other nights there are jungle parties inland and loud beach bars. Srithanu offers sunset bars and sober ecstatic dance as a gentler night out.

On Langkawi, going out means bean bags on the sand at Pantai Cenang, fire-twirling shows and cheap duty-free drinks among couples and families. There are no clubs of note, and the island is dark well before midnight. That suits anyone who wants to sleep, but party-goers will be disappointed.

Langkawi has the more striking landscape on land. The whole archipelago is a UNESCO Global Geopark. You can take a boat or kayak through the mangroves and limestone cliffs of Kilim, ride the cable car up the Machinchang range to the sky bridge, and look for hornbills and dusky langurs on Gunung Raya, at about 880m the higher of the two islands' peaks.

Koh Phangan's forested interior has trails up to Khao Ra and waterfalls that are fullest after the rains. Its real strength is out at sea, with diving at Sail Rock, where whale sharks appear in some seasons, and boat trips to the lagoons of Ang Thong National Marine Park.

Koh Phangan has more to offer within a day. Koh Samui is about half an hour away by ferry, with the Big Buddha and Fisherman's Village in Bophut. Koh Tao is a little over an hour to the north for snorkelling around Koh Nang Yuan.

From Langkawi the choices are harder work. Koh Lipe means a border crossing. The ferries to Kuala Perlis or Kuala Kedah lead to Alor Setar's mosque and old centre, but that makes a long day for a modest reward, so most visitors take boat trips around the island instead.

Langkawi is the easier island for a family. Pantai Cenang and Pantai Tengah have warm, shallow water, and many resorts have kids' clubs. Underwater World, the cable car, eagle-feeding in the mangroves and a wildlife park near Kuah will fill several days, even if the list runs out within a week.

Families can manage on Koh Phangan if they stay in the calm northern bays such as Thong Nai Pan or Haad Yao. But nothing there is built for children, the roads are steep and full of scooters, and Haad Rin around the full moon is no place to bring them.

Langkawi is by far the easier island to drive, and on Koh Phangan you notice the difference within a day. On Phangan most people end up on a rented scooter, because shared songthaews from the pier are the only alternative to app taxis. The hill roads are steep and gravel in places, accidents among inexperienced riders are common, and Bottle Beach is easiest to reach by longtail boat. Distances are at least short.

Langkawi is about 25km across, with good, quiet roads, cheap car hire and ride-hailing apps that work well. Nothing is more than about forty minutes away, and the airport is next to Pantai Cenang.

Langkawi gives shoppers a clearer reason to come. The whole island is duty-free, and the big complexes in Kuah and along Pantai Cenang sell chocolate, alcohol, cosmetics and kitchenware, alongside batik sarongs and pearl stalls.

Koh Phangan's shopping is more casual. It offers loose cotton clothes and snacks at Thong Sala's Saturday walking street, neon party wear in Haad Rin and yoga clothing and crystals in Srithanu. On neither island will you find fashion streets or crafts worth a special trip.

Both are cheap islands for most visitors, but the costs rise in different ways. On Koh Phangan the moon sets the price. Simple bungalows and long stays on the west coast are very cheap, while rooms in Haad Rin around the full moon cost several times the usual rate and often require a minimum stay.

On Langkawi it comes down to where you sleep and what you book. Car hire, fuel, night-market food and duty-free beer cost little, but the rainforest luxury resorts, the cable car and boat tours add up quickly.

Koh Phangan has a little more live music, and more of its own character. Around Srithanu and the west coast, beach bars hold acoustic sets, open-mic and reggae jam nights. The ecstatic-dance and sound-healing gatherings bring their own music, and fire-dancers perform on the sand at Haad Rin.

On Langkawi the music is thinner and more of a show put on for visitors. You will find cover bands in a few bars, fire-dancing on Cenang beach and now and then a Malay cultural show over a resort dinner. Neither island has a theatre or concert hall, so for real performances you have to go to the mainland.

Koh Phangan is the place to come for a retreat. Around Srithanu there are yoga shalas, silent and meditation retreats, detox programmes, breathwork and sound healing, and people often stay for weeks. Wat Khao Tham adds a long tradition of Buddhist meditation retreats.

Langkawi's calm comes from its slow pace and its resort spas rather than from courses. The rainforest resorts in the northwest and at Tanjung Rhu offer treatments based on Malay herbal traditions, and Pantai Cenang has cheap reflexology shops. A small hot spring near Kuah is the only bathing on offer.