Train travellers on busy commuter routes are the ones least satisfied with their service, according to a Which? survey.
Services from south east England into London are also the most likely to be delayed, the poll of 7,000 train travellers found.
Passengers with the Southern train company experienced the most delays, while those least satisfied overall with their service were customers travelling on Thameslink and Great Northern/First Capital Connect (TGN/FCC) routes.
While TGN/FCC's overall satisfaction score was only 43%, Grand Central, which was at the top of the satisfaction table, had a score of 76% - with First Hull Trains getting 69% and Merseyrail scoring 64%.
At the other end of the table, Southeastern got only 44%, with Southern and Abellio Greater Anglia scoring 46%
The table was based on responses from 7,309 commuter and leisure travellers based on journeys they had taken in the 12 months ending November 2014.
Areas covered included availability of seating, cleanliness of toilets and carriages, punctuality and value for money.
Travellers were also asked if they had experienced a delay on the last journey they had taken with their train company. On this basis Southern had the worst score, with 39% of passengers experiencing a delay.
Next-worst for delays was TGN/FCC, Southeastern and First Great Western (FGW) with scores of 33%.
The fewest delays were on c2c, with only 14% of passengers experiencing a hold-up on their last journey.
Overall, 29% of rail passengers said they had suffered a delay when they last travelled, while three quarters of those held up for more than an hour said they were not told that this meant they qualified for a full refund.
Which? said the best operator for letting passengers know their rights on delays was London Overground, who told 38% of customers when they were entitled to a full refund on their last journey.
They were followed by South West Trains (33%), Southeastern (31%), FGW (27%). Last was Southern, where only 19% were informed about compensation.
Which? executive director Richard Lloyd said: "Long delays and consistently low levels of customer service are driving commuters to distraction.
"Passengers often have little or no choice as to the rail companies they travel with, so as ticket prices continue to rocket, more must be done to improve customers' satisfaction and to inform people of their right to a refund as a result of delays."
Martin Abrams, public transport campaigner for the Campaign for Better Transport, said: "The Which? survey paints a bleak picture of expensive fares, frequent delays, overcrowded, dirty trains and poor communication from train companies to passengers.
"It is very notable that some of the busiest train routes around London and the South East are also regarded as offering the worst value for money. It's also telling that those franchises which are managed locally rather than from Whitehall tend to offer a better service."
He went on: "Passengers need the train companies and Government to up their game.
"There needs to be an end to the perpetual wage-busting fare hikes and more devolving of control away from the dead hand of Westminster and toward people on the ground who know best what the priorities for passengers are."
David Sidebottom, director at rail customer watchdog Passenger Focus, said: "Passengers have told us that punctuality and how well train companies deal with delays are the biggest factors in whether they are satisfied with the overall service.
"The top issues raised by passengers contacting Passenger Focus include train delays, refund conditions and levels of compensation."
He went on: "This is a problem that needs addressing. When trains are delayed or cancelled, it is important that passengers are made aware of their rights to a refund or compensation. We want train operators to do more to inform passengers of their rights.
"For commuters, we want train operators to recognise the impact on work and home life of frequent delays under 30 minutes by offering some recompense."
A spokesman for the Rail Delivery Group, which represents rail operators and Network Rail, said: "The timetable is our promise to passengers. While almost nine out ten trains now arrive on schedule, we are investing billions of pounds so that we make good on that promise more often and improve passengers' satisfaction with our services.
"Compensation payments are increasingly generous and easy to apply for and are often made regardless of the cause of a delay. This is why the amount paid out to passengers under the Delay Repay scheme increased by £10 million between 2013 and 2014, despite punctuality improving over that period. "
Shadow rail minister Lilian Greenwood said: "The Which? report underlines the need for rail industry reform - reforms David Cameron's Government have been unwilling to consider at a time when fares are up by more than 20% since 2010.
"Passenger satisfaction is still shockingly poor. Labour will institute a new body for running the railway which will have a strong voice for passengers at its heart."
Rail Minister Claire Perry said: "As part of our long-term economic plan, we are investing record amounts in the rail network in order to give passengers better journeys.
"It is vital that, as the industry delivers these essential improvements for the future, it does everything it can to minimise disruption in the present.
"We expect the industry to provide the best possible customer experience every day. When things go wrong unexpectedly, it must ensure passengers are kept informed about the compensation they are entitled to."
This table, from Which?, shows the proportion of passengers who experienced a delay on their last journey with each train company:
1. Southern 39%
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%
13. Arriva Trains Wales 26%
14. East Midlands Trains 25%
15= East Coast 23%
15= Virgin Trains 23%
17. ScotRail 19%
18. Grand Central 17%
19= First Hull Trains 15%
19= Merseyrail 15%
21 c2c 14%