Koh Phangan or Penang?

Koh Phangan has much the better beaches. The north has twin bays at Thong Nai Pan and a longtail ride to Bottle Beach, with deep, calm water. The northwest has Haad Yao and Haad Salad for easy swimming, and Mae Haad has a sandbar walk to Koh Ma for snorkelling. Even its weaker stretches, the shallow reef flats of the south, give good sunsets.

Penang's sea is just as warm, but the main strip at Batu Ferringhi is busy with jet skis, often cloudy, and visited by jellyfish at times. The nicer sand at Monkey Beach and Kerachut in the national park takes a forest walk or a boat to reach and has few facilities. A swim there is something extra on the day, not why you came.

Penang is one of Asia's great places to eat, and Koh Phangan is not in the same league. George Town's hawker centres and old coffee shops bring Hokkien, Malay, Tamil and Nyonya cooking side by side: char kway teow off the charcoal, assam laksa, banana-leaf rice in Little India and cendol in the afternoon heat. Planning the day around meals is the normal thing to do there.

On Koh Phangan you will eat well but simply. The best of it is curries, grilled fish and som tam at Thong Sala's evening market and Saturday walking street, while Srithanu serves vegan and raw food to the yoga crowd. The menus in the resort bays are often toned down for visitors.

Here the gap is wide. George Town was built over two centuries of trade between China, India, the Malay world and Britain, and you see it in the carved Khoo Kongsi, the clan jetties on stilts, the blue Cheong Fatt Tze Mansion and the line of temples, mosques and churches on Harmony Street. Two or three days of walking barely covers it.

Koh Phangan has no museums or historic towns. Its sights are Wat Phu Khao Noi, the meditation temple of Wat Khao Tham and the royal initials carved at Than Sadet, which together fill a quiet afternoon.

Koh Phangan is the place for a big night out. The Full Moon Party brings tens of thousands to Sunrise Beach at Haad Rin, with sound systems running past dawn, and half-moon and jungle parties fill the nights in between. It is a narrow scene of sand, bass and young backpackers, and the west coast offers sunset bars and sober ecstatic dance instead.

Penang's evenings are gentler and mostly spent drinking. Backpackers fill the bars of Love Lane and Chulia Street, Upper Penang Road has a few late bars and clubs, and restored shophouses serve cocktails. Plenty of nights simply end at a hawker stall.

The two are about even, but the outdoors means different things on each. Koh Phangan's best is offshore. You can dive Sail Rock, where whale sharks sometimes pass, or take a boat to the limestone islands and lagoons of Ang Thong. On land, steep forest trails lead to Khao Ra and to waterfalls that run fullest after the rains.

Penang's nature is on the island itself and easier to get to. A funicular climbs Penang Hill to cooler air and a canopy walkway, coastal trails in the national park lead to a lighthouse and turtle beaches, and the orchards and fishing villages around Balik Pulau are good for cycling.

Penang has more within a day's reach because it is tied to the mainland. Ipoh, about two hours away by train, has a colonial old town and cave temples in limestone hills. Taiping's lake gardens can be combined with royal Kuala Kangsar, and the Bujang Valley holds early temple ruins.

From Koh Phangan, every outing is a ferry. Koh Samui gives you the Big Buddha and Fisherman's Village, and Koh Tao gives you a day of snorkelling around Koh Nang Yuan. Beyond those two neighbouring islands there is little to go to.

Penang gives children more to do. Teluk Bahang has a water and adventure park, a butterfly and insect park and a spice garden. They can also ride the funicular up Penang Hill, watch the macaques in the Botanic Gardens and visit George Town's interactive museums, though its stepped walkways are hard with a pushchair.

Koh Phangan's strength for families is the sea itself. Thong Nai Pan, Haad Yao and Haad Salad have gently shelving sand and calm water. There is nothing built for children, though, the hill roads are full of scooters, and Haad Rin around the full moon is no place for a family.

Penang is easier to get around. George Town's heritage core can be walked or covered by trishaw and bicycle, buses run out to Batu Ferringhi, and cheap ride-hailing fills the gaps. Butterworth's railway station is a short ferry crossing away.

On Koh Phangan you depend on songthaews waiting at the pier, app taxis or a hired scooter. The hill roads are steep and sometimes gravel, and accidents are common among new riders. Distances are short, but Bottle Beach and the far eastern bays are slow to reach.

Neither island is a shopping destination, but Penang offers more. There are air-conditioned malls along Gurney Drive for everyday brands. Old George Town has antique shops, studios selling Peranakan beadwork and batik, and fabrics, spices and gold in Little India.

Koh Phangan's shopping is a short list of casual buys. You will find cotton clothes and snacks at the Saturday walking street in Thong Sala, neon party wear in Haad Rin and yoga clothing and crystals in Srithanu.

Both are cheap, and Penang is cheaper. Hawker meals and ride-hailing cost very little, and most temples and clan houses are free or nearly so. Alcohol is the exception, because tax makes beer and wine dear compared with food.

On Koh Phangan, a beach bungalow, local Thai meals and scooter hire keep a long stay on the west coast inexpensive. Boat transfers, the Srithanu retreats and the boutique resorts in the north add up, though. Rooms in Haad Rin around the full moon cost several times the normal rate.

Neither island has much to offer here, but Penang has more. The yearly George Town Festival fills the heritage streets with theatre and dance, a north-coast arts centre stages local plays, and temple festivals bring Chinese street opera and puppet shows.

Koh Phangan's performances are informal. There are acoustic and open-mic nights in west-coast beach bars, music at the ecstatic-dance gatherings and fire-dancers on the sand at Haad Rin.

For a restorative stay, Koh Phangan is far ahead. Srithanu and the west coast are given over to yoga shalas, silent retreats, detox programmes and sound healing, Wat Khao Tham offers Buddhist meditation, and the northern bays have hammocks and early nights. Many people come for a course and stay for months.

Penang's version is daily foot reflexology and Chinese or Malay massage, cheap enough to have every day, plus the spas of the Batu Ferringhi resorts. For real quiet you have to head up to the cool air of Penang Hill or out to Balik Pulau.