Colossal ideas... or the makings of a white elephant?

You know the Angel of the North. Now imagine the Colossus of the South. It will stand near Ebbsfleet International station, to amaze Eurostar passengers as they travel through Kent. It will cost £2m and stand 50 metres high.

The plans were unveiled yesterday at a nearby project centre. Five invited artists are up for designing it: Mark Wallinger (last year's Turner Prize winner), Rachel Whiteread, Richard Deacon, Christopher Le Brun, and the Frenchman Daniel Buren. Their proposals are a horse, a house, a cellular structure, a wing and a tower of tables. Most of them are white, but please don't say elephant.

The Ebbsfleet Landmark is the project's working title. When it is erected (due date 2010) it will be Britain's tallest statue. But what it is dedicated to is anyone's guess. There is something arbitrary even about its stature: 50 metres was required by the Highways Agency so it wouldn't take drivers by surprise – they'll see it coming for miles.

Daniel Buren's scale model looks like a nest of Ikea tables, with the smallest on top. A beam of light shoots skywards from an altar in the middle of it. It suggests a temple from a sci-fi civilisation.

Christopher Le Brun envisages an enormous concave dish fronted by an enormous wing. It's like a logo that might be used by a 1950s airline, or even a petrol company.

Richard Deacon's steel framework of 26 wonky polyhedrons is a real 3D creation. It offers a multi-angled experience, generating a succession of shifting and unstable forms, as you try to get your head round its complex crystal structure. A good sculpture, probably – but one perhaps better seen at a distance.

Rachel Whiteread's idea is to take a typical Whiteread piece – a concrete cast of the inside space of a house – and set it on a precipitous artificial crag.

Mark Wallinger's concept is the simplest: a white horse, a realistic effigy of a thoroughbred but 33 times the size of any real horse.

The artists' brief was to put Ebbsfleet on the map. But Ebbsfleet Valley is the name of a "mixed-use" development that will unfold over the next 20 years. Right now there's only a station and a vast brown field. So the landmark is meant to give an identity to something that isn't there. It is an exercise in pure branding. It appears that all it needs to be is conspicuous.

For the next few months the proposals will be on display at the Bluewater Shopping Centre nearby. The winner will be chosen by a panel of judges in the autumn. The landmark is intended to establish an identity, so the sculpture itself must have a strong identity. It mustn't be too vague or complicated. It must be memorably simple.

Mark Wallinger's white horse seems to fit the bill best. It's rich in English symbolism: white horses on hills, the sport of kings. And it's nicely normal – a horse being something you often see from a passing train.