Train commuters from the south-east of England into London are more likely to face delays than anywhere else in the country, according to new figures.
The survey, by consumer watchdog Which?, also found travellers on busy commuter routes were the most dissatisfied with the service received.
It comes as official figures from the Office of Rail Regulation revealed passengers are ploughing more and more money into the rail industry, largely thanks to fare hikes - while government contribution is dipping.
A financial report revealed income from passengers in 2013/14 was £8.16 billion - a 10.8 per cent rise compared with the figure for 2010/11 and 6.2 per cent higher than in 2012/13.
Meanwhile, government funding for the railways in 2013/14 was just under £3.8bn - a 16.4 per cent drop on 2010/11 and 8.1 per cent down on 2012/13.
According to the Which? survey of more than 7,000 passengers, those travelling with Southern experienced the most delays, with 39 per cent of people saying their last journey with the operator had been running behind schedule.
ITV News Correspondent Richard Pallot reports:
Meanwhile, Thameslink and Great Northern/First Capital Connect (TGN/FCC) came bottom of the satisfaction charts, with just 43 per cent of people saying they were pleased with the service.
Satisfaction bottom four
Abellio Greater Anglia: 46%
Grand Central came in highest for satisfaction, with a score of 76 per cent, followed by First Hull Trains at 69 per cent and Merseyrail at 64 per cent.
The passengers were asked their views on availability of seating, cleanliness of toilets and carriages, punctuality and value for money, as well as delays.
Overall, 29 per cent of passengers said they had suffered a delay when they last travelled - and three-quarters of those who said they were held up for more than an hour said they were not told they qualified for a full refund.
Campaigners have now called for action on poor customer service.
Martin Abrams, from the Campaign for Better Transport, called for rail firms and the government to "up their game".
Which firm is worst for delays - and which is the best?
2= Thameslink & Great Northern / First Capital Connect 33%
2= Southeastern 33%
2= First Great Western 33%
5= First TransPennine Express 30%
5= Greater Anglia 30%
7= CrossCountry 29%
7= London Overground 29%
7= London Midland 29%
10= Northern Rail 28%
10= Chiltern Railways 28%
10= South West Trains 28%
15= East Coast 23%
15= Virgin Trains 23%
19= First Hull Trains 15%
19= Merseyrail 15%
21 c2c 14%
A spokesman for the Rail Delivery Group, which represents rail operators and Network Rail, said: