London has eight Royal Parks, so let's stage a knockout competition to see which is the best.
n.b. Due to a lack of interactive voting technology I'll be knocking out the parks myself rather than taking collective input, but that's fine because I intend to reach the correct final conclusion anyway.
St James's Park v Green Park
We start with a fairly straightforward battle. Both are central London classics, nudging up against Buckingham Palace and brimming with tourists. But whereas St James's Park has several points of interest, and better-performing squirrels, its neighbour is quite frankly a bit dull. Green Park is well named, being almost entirely green grass and (at this time of year) green trees. It has no lakes, just a small fountain, and no buildings, just a couple of war memorials. More to the point it has no flowers other than springtime narcissi, and you've just missed those, plus avenues of plane and lime trees for shady promenading. Sure it's pleasant to sit in, but there's little you can point at and go wow. St James's Park by contrast has that lovely central lake (landscaped by John Nash), a cute little cottage with a vegetable garden, more than one place to buy drinks, two islands, a bridge with fine views of the palace and a war memorial of its own. It also contains the Stevenson screen that measures central London's official weather, a choice of woody or grassy flanks and best of all it has pelicans, for heaven's sake. An absolute walkover for the saint.
Bushy Park v Richmond Park
These by contrast are sprawling deer parks in the outer boroughs, huge rambling spaces with acres for everyone. Richmond Park is the larger, by some distance, indeed probably the largest undeveloped wilderness in the capital. Not only is it great for walking, there always being another corner to explore, but it's quite the place for cyclists too. It boasts a scenic river and a central wetland, a proper hill overlooking Petersham with a protected view from the summit, ten listed buildings and innumerable woods. It also has the Isabella Plantation, a pristine horticultural enclave that bursts into photogenic gorgeousness at this time every year. It's plainly the winner here, or so I assumed before I reminded myself of Bushy Park by taking a long walk there yesterday. It has that classical fountain surrounded by a giant pool where lengthy chestnut avenues meet, it has plantations, ponds and an ornamental river, and it has a fenced-off Water Gardens by the Admiralty Cascade. It has deer you can get right up close to, if you can find them, which admittedly Richmond has too but here they're easier to find. It also has a properly dazzling display of rhododendrons, azaleas and camellias in the Waterhouse Woodland Gardens with pinks and golds and oranges to excess, or at least it does at present, perhaps I visited in precisely the right week. My walk still didn't quite convince me Bushy should win this bout, Richmond still takes the crown, but it's closer than I thought.
Semi-Final 1: St James's Park v Richmond Park
No contest, either in scale or in interest, it's got to be Richmond.
Hyde Park v Kensington Gardens
Most Londoners probably think of this rectangular slice of central London as all being Hyde Park, which indeed it used to be until 1728 when Queen Caroline divided it in two. She nabbed the western half as gardens for her palace, hence that became Kensington Gardens, plus it's also entirely her fault that the Serpentine was created. These days the dividing line is West Carriage Drive, the road that wends down the middle, with the Serpentine duly shared but most of it on the Hyde Park side. The knockout battle therefore comes down to which half has the better stuff. Hyde Park has Speaker's Corner, the rose garden, boat hire, the lido where brave souls go swimming, the slippery Diana Memorial Fountain, Winter Wonderland's seasonal pitch, the site of the Great Exhibition, a police station and a backhistory of hundreds of outdoor concerts. Kensington Gardens obviously has Kensington Palace but also the Albert Memorial, both halves of the Serpentine Gallery, the Round Pond, most of the statues (including Peter Pan), the Flower Walk, the Italian Gardens and the adventure playground. That's quite well matched although arguably KG has more to offer whereas HP is more about open space. One thing that swings it for me is that Kensington Gardens closes at dusk whereas Hyde Park has after dark access, plus the historical truth that it was all once Hyde Park and Hyde Park is how it's best known, so Hyde Park it is.
Greenwich Park v Regent's Park
The last two Royal Parks don't form a natural pair, indeed they're seven miles apart. Greenwich Park is arguably the oldest of the Royal Parks, having been enclosed in the 15th century, and was the site of Henry VIII's palace of Placentia. It can also boast the National Maritime Museum, the Queen's House and Greenwich Observatory. The fact a meridian passing through the park defines global time is a huge boost, reputationwise, and the view from the top of the hill across the Thames towards Docklands is pretty spectacular. Let's also not forget the Rose Garden, the ornamental enclave and the Wilderness where the deer live (although they're not there at present, they've been moved to Richmond Park, which probably says a lot in terms of ranking). Meanwhile Regent's Park is a late Georgian phenomenon, the landscaped plaything of the Prince Regent, and a more extensive matter. Not only does it have a canal, a boating lake, a Broad Walk and an Outer Circle, it also boasts probably the best rose garden in London. Its buildings are arguably better than Greenwich's, including a university, an open air theatre and an ambassador's hideaway, plus the slamdunk attraction that is London Zoo. Throw in the fact that Primrose Hill is now included as a bolt-on, and that has to mean victory for Regent's Park.
Semi-Final 2: Hyde Park v Regent's Park
This is possibly the toughest contest yet. Both parks are similar in size (Regent's is slightly bigger) and contain a mix of recreational space, elaborate landscaping and somewhere to hire a boat. Both are known worldwide and provide a welcome oasis in the heart of the capital. In the end it comes down to whether you prefer open and simple (Hyde Park) or busy and feature-packed (Regent's Park). Of the two I think I prefer walking freely across Hyde Park to manoeuvring around Regent's Park... but ultimately it doesn't matter, because whichever park I pick it's getting trounced in the final.
Final: Richmond Park v Hyde Park
Three and a half square miles of wilderness in all its natural variation easily beats a nice park just off Oxford Street. When a Londoner is tired of Richmond Park they are tired of life.