At the moment, the demand for Mk1 Focus is centred heavily around the RS. It's not always easy to match up a car that you want and one that will appreciate, so be prepared to decide what's most important. But we reckon the ST170 is a good shout. You might not find a fantastic example for the money, but you could save up a bit longer and get one. Whatever you do, be sure to set aside some money for maintenance - no car is ever fault-free and this generation of modern classics is reaching a point where they will need some money spending on them to keep them going. Make sure you do your homework on insurance, too - there's no hard and fast rule about what is and isn't a classic so if you're looking to get one a classic policy not every insurer might be able to offer one. Like you say, the Mk1 Focus was a gamechanger, but it will take time to appreciate as a classic - purely because there were so many of them.