Troubled train company First Great Western (FGW) has come bottom of a passenger satisfaction league table.
FGW is struggling to improve punctuality and cut overcrowding
Independent rail consumer watchdog Passenger Focus sampled 50,000 people in its National Passenger Survey.
Only 74% of the Swindon-based firm's passengers were satisfied with their journeys - the national average is 81%.
Peter Andrews, from the campaign group, More Train Less Strain, said: "I'm not at all surprised. This is why our fare strike on Monday will be going ahead."
Next week's proposed action follows repeated criticism of the firm over poor service, delays and overcrowding.
The survey also found that fewer than half of FGW's passengers were happy with the price of tickets, the ability of the company to deal with delays, and the state of the toilets.
FGW announced this week that it would double the amount of compensation paid to season ticket holders for delays after it failed to meet its punctuality and reliability targets.
The company has blamed a shortage of rolling stock and staff.
"We've been getting the same apologies for a year, but their profits continue to go up," said Mr Andrews.
"They're more interested in giving their shareholders a large return, rather than providing the public with a punctual, affordable and reliable railway."
A statement from First Great Western said many of the problems were due to the "old and fragile infrastructure" on which the trains ran, but that it was working hard with Network Rail to tackle the issues.
"First Great Western is introducing a new management structure with more highly-experienced railway professionals now running the company," it said.
"We are investing £200m to improve trains and stations and this work is already beginning to produce excellent results."
The company added that it was also recruiting more drivers and guards to boost reliability.