Ask 100 people, and you’ll probably get 100 different answers! I’m going to list a few options that you might like to consider if you don’t have any personal preferences and are looking for something affordable, easy to maintain, and inexpensive to run.
Classic Mini: A truly iconic classic. Plenty are available to choose from, with parts readily available and affordable. Some repairs may be better left to an expert, but generally, it’s an enjoyable car to own.
Morris Minor: A very popular classic. Most tasks can be completed by a competent enthusiast, and parts are easily available and inexpensive.
MGB Roadster: Possibly the ultimate first classic sports car, it’s relatively easy to work on has brilliant parts availability and club support.
Ford Anglia 105E: Perhaps the most distinctive Ford to come out of the 1960s. Easy to work on parts readily availabe one of my favourite classics!
A few others you wish to consider Austin 1100 / 1300, Austin A30 / A35, Wolseley 1300 / 1500, MG Midget, Triumph Herald, Triumph Spitfire, Morris Oxford, Ford Cortina, Fiat 126, Fiat 500, Hillman Minx, Singer Vogue, Humber Sceptre, Ford Escort,