The vast majority of rail commuters believe there has been no improvement in their train service during the past year, despite the much-criticised rise in rail fares.
Around 67% of commuters think the service from their train company has stayed the same and 13% believe it has got worse, research for consumer group Which? found.
Just one in five respondents have noticed an improvement.
Southern achieved a customer satisfaction score of just 28%, putting it in last place for the third year running in the annual survey, after a string of delays caused by strike action over the last year.
The operator scored just one star out of five for value for money, reliability and punctuality, and two stars for all other categories. More than a third of Southern commuters think the service has got worse in the past 12 months.
Grand Central topped the Which? table, receiving an overall score of 64% and four stars in all categories. A total of 2,865 UK commuters were polled in October and November.
Alex Hayman, managing director of public markets for Which?, said: "Fares are going up but frustrated and long-suffering passengers affected by seemingly never-ending delays, cancellations and dirty trains don't feel that their services are getting any better.
"The problems don't stop there. People are also finding it difficult to claim compensation when things go wrong. Automatic compensation must be introduced across the industry so that people can get the money they are owed.
The National Audit Office said last week that the Department for Transport made decisions in setting up the Thameslink, Southern and Great Northern franchise which "have negatively impacted on passengers."
Passenger watchdog Transport Focus is also due to release passenger satisfaction figures in two weeks' time, after gaining responses from roughly 25,000 rail travellers.