It is inevitable in an industry that’s as old and far reaching as ours that every year brings a smattering of significant anniversaries. Even so, I think 2013 has more than its fair share and you can expect the motoring media to spend a fair chunk of the months to come shrouded in misty-eyed nostalgia.

We have the Aston Martin centenary and a half century for Lamborghini. The Le Mans 24 Hours hits 90 this year, while Caterham Cars celebrates 40 years as a manufacturer in its own right. Even the Goodwood Festival of Speed which spends much of its time celebrating other anniversaries has one of its own: it seems extraordinary to me but it really is 20 years since we first trooped down to Goodwood House to watch a relatively small number of racing cars and bikes slip, slither and slide their way up the hill.

But for me at least, there is one anniversary that trumps the lot. At the Frankfurt Motorshow 50 years ago, Porsche pulled the covers off a new sports car designed as a faster, more comfortable, practical and powerful replacement for the stalwart 356. It called it the 901 until Peugeot cried foul and asserted its rights to three figure numbers with a zero in the middle. Porsche simply added 10 to the number and the 911 was born.

It became not only the most enduring sports car of all time and easily the most successful road-derived racing car, it also proved its mettle on events as gruelling as the Monte Carlo rally (which it won three times on the trot) and the Paris-Dakar. It is the most important sports car that has ever been designed.

But which is best? RS models command vast price tags, but what about cars mere mortals might be able to afford?

Best ‘classic’ 911

Sadly early 911s have moved out of financial sight for most. The best non-RS model is probably the 2.4-litre 911S of the early ‘70s but I’ve seen asking prices for clean examples touching six figures.

Instead for rather less than £20,000 you can buy 3.2-litre 911 Carrera built between 1984 and 89. The best cars are the later models fitted with the excellent G50 gearbox rather than the old and obstructive 915 (if you’re not sure, reverse is top left on a G50, bottom right on a 915). These cars have outstandingly smooth motors, performance that’ll still dust most new cars and first class build quality.

Best value 911

It’s still the 1977-84 SC, especially when fitted with the later 204bhp version of the 3-litre motor. These cars are legendarily durable thanks to their fully galvanised bodyshells (earlier 911s can rot horrifically) and perhaps the strongest version of the flat six engine. The engine is understressed and produces all its urge in the mid-range so it’s fabulously usable too. Prices are now rising but excellent examples are still available for under £15k or, put another way, a the price of a mid-spec diesel Ford Fiesta.

Best 911 to use everyday

For the money (under £25,000), a first generation 997 is hard to beat. A substantial step forward in all areas over the unloved 996 it replaced, these cars still drive like new and, so long as the well documented issue with the engine’s rear main oil seal has been addressed, are exceptionally reliable.

Best overall

It has to be the last of the air-cooled cars. The 993-series was the ultimate development of the original theme and so well built Porsche almost went bust. They were also the first 911s with near enough all their handling foibles removed thanks to a completely different design for its rear suspension. Which to get? As with all 911s, remember that less is almost always more: forget tiptronic transmission, targa roofs and four-wheel drive hardware and just get a basic, manual Carrera 2 coupe. Prices for nice ones are around £20,000 for now, but it’s hard to see them staying there forever.

And one to avoid…

If you must have a 911, then the 996 series built between 1997 and 2005 will clearly be tempting. For as little as £8500 you can buy a 300bhp 911 that’ll still feel properly fast and handle remarkably well. But there’s a reason they’re as cheap as they are: this is easily the worst built 911 of all, as Porsche cut every corner it could to save itself from financial oblivion. Interiors age quickly and because they’re not worth much, many are now in a sad state of neglect. A good one with the engine oil seal issue resolved is still a bargain, but if it’s the real 911 experience you’re after, you’ll need to pay a little more and shop elsewhere.