In the north-west corner of Trafalgar Square there is a plinth. From 1841 until 1999 it stood empty, but more recently it's become a location for high-profile contemporary art, commissioned from leading artists, with each work being housed on the plinth for a year or two. This is mainly thanks to the RSA who initiated a programme of new commissions for the plinth in 1998.

The first piece that went up was by recent Turner prize winner Mark Wallinger. He created Ecce Homo, the rather elegant life size Christ figure, in 1999. Then Bill Woodrow had a go with Regardless of History, the book and tree sculpture, in 2000. Rachel Whiteread created Untitled Monument in 2001, an inverted resin cast of the plinth, which if you looked at it upside down, looked a bit like the entire planet had been put on a plinth.

In June 2002, a David Beckham waxwork model had an unauthorised appearance, but the GLA didn't let that last too long.

Marc Quinn's fantastic sculpture Alison Lapper Pregnant was next, from September 2005 to last October, neatly referencing the nearby one-armed Nelson. It was the first commission from the Fourth Plinth Commissioning Programme (after responsiblity for Trafalgar Square was transferred to the Mayor and the Greater London Authority).

The second in that series is Thomas Schütte’s sculpture Model for a Hotel, which was unveiled in November. It's made of a specially engineered glass (in yellow, red and blue) which collects light and reflects it through its edges. We think it looks a lot more 1987 than 2007, which is either a good thing or a bad thing, depending on whether you experienced the 80s or not.

The six proposals for the next piece to go up have just been unveiled, and are on show at the National Gallery from now until 30 March. The lucky winner will be announced by the Mayor later in the year.

We really like the Fourth Plinth project, so we've decided to show all the proposals here, together with the explanations for each piece.

The Spoils of War (Memorial for an unknown civilian) Jeremy Deller

"‘The presentation of the spoils of war to a curious public dates back at least to the Roman Empire. My idea for the fourth plinth performs a similar role’, says Jeremy Deller, ‘It is not an artwork, but the remains of a vehicle that has been destroyed in an attack on civilians in Iraq’."

Something for the Future Tracey Emin

"For some years Tracey Emin has been interested in the social behaviour of meerkats, small mammals that live together in an egalitarian order in the Kalahari Desert, southern Africa. She has noticed that ‘whenever Britain is in crisis or, as a nation, is experiencing sadness and loss (for example, after Princess Diana’s funeral), the next programme on television is Meerkats United’. Emin proposes to place a sculpture of a small group of meerkats on the empty plinth as a symbol of unity and safety."

One and Other Antony Gormley

"Antony Gormley proposes that the fourth plinth is occupied 24 hours a day by members of the public who have volunteered to stand on it for an hour at a time. Over a period of 12 months, 8,760 people would take part. ‘Through elevation onto the plinth and removal from common ground’, explains Gormley, ‘the subjective living body becomes both representation and representative, encouraging consideration of diversity, vulnerability and the individual in contemporary society’. This is particularly pertinent in the context of Trafalgar Square with its military statues honouring specific individuals."

Sky Plinth Anish Kapoor

"Sky Plinth literally brings the clouds down to the ground ‘displaying’ the changing sky-scape as a ‘monument’ on Trafalgar Square. The five concave mirrors cantilever off the plinth treating all its faces as supports. The plinth is thought of as an object which is dematerialised by the mirrors. They turn the world upside down and in so doing bring the sky down to the ground."

Nelson’s Ship in a Bottle Yinka Shonibare

"Turner nominated Yinka Shonibare proposes to make a scale replica of Nelson’s ship, HMS Victory, in a giant glass bottle. The ship’s magnificent sails will be produced in richly coloured and patterned textiles, which Shonibare buys from Brixton market in London. They are assumed to be African but in fact the fabric was inspired by Indonesian batik design, mass produced by the Dutch and sold to the colonies in West Africa. By the 1960s the material was popularly assimilated in Africa and became symbolic of African identity and independence. Shonibare says his piece will reflect the story of multiculturalism in London today, which began as a result of Nelson’s victory at the Battle of Trafalgar: ‘For me it’s a celebration of London’s immense ethnic wealth, giving expression to and honouring the many cultures and ethnicities that are still breathing precious wind into the sails of the UK.’"

Faîtes L’Art, pas La Guerre (Make Art, Not War)
Bob & Roberta Smith (aka artist Patrick Brill)

"This illuminated peace sign – powered by the sun and the wind – questions our ideas about history and monuments on the one hand, and art and war on the other. The work, which is a collaboration between renewable energy specialists, structuralengineers and an architect, seeks to rebrand Trafalgar Square as a beacon of our cultural future rather than a memorial to England’s military past. Bob & Roberta Smith believe in ‘the power of art to act as a social force as great and necessary to our lives as the police, the military and the judiciary’; their proposal is meant as a ‘gentle provocation to the overwhelming “Hogarthian” stature of Trafalgar Square as the centre of celebration of Britain’s military achievements over the French’."

We like Deller's piece, though we can't see the GLA going for it; Emin's is funny (which is no bad thing - art doesn't have to be serious, though it should make you think); Gormley's has the whiff of homework done on the bus on the way to school; Kapoor's is interesting, but not as elegantly simple as his best work; Shonibare's is great, but the pigeons would make a right old mess of it; and Bob and Roberta Smith's is a nice idea, but a bit cluttered for our tastes.

We're voting for Deller.

If you fancy telling the commission what you think, there's an online public consultation form here.

(Photos of models by James O Jenkins; photo of Alison Lapper Pregnant by Trois Tetes)