Mixed view in rail passenger survey
But other customers are more satisfied with their rail journeys, showing that "some train companies are getting it right", the magazine said.
Based on responses from 4,092 adults, the survey revealed that Virgin Trains, which operates the West Coast line, was considered the best train company. Next was the London to Tilbury and Southend company c2c, followed by Merseyrail, East Coast and East Midlands Trains.
London Overground was seen as the most improved commuter company, with 45% saying it had got better, but with 21% reckoning it had got worse.
Bottom of the table was Southeastern, with its customers citing "overcrowding and high fares, with perceived cuts to services". Some Southeastern passengers did praise new high-speed trains, with 34% reckoning the overall service had got worse, but 23% saying it had got better. The next least popular companies with customers were National Express East Anglia and First Capital Connect.
The results were based on combining scores based on views from leisure and commuter travellers. Taking commuter services alone, the top company was c2c, with London Overground second. Many people said London Overground's new trains were "lovely".
Which? said that Southeastern, which was last in the commuter service table, had told the magazine it was disappointed with the results. Southeastern said a passenger survey carried out by rail customer watchdog Passenger Focus showed that 83% of passengers were satisfied with the service.
Which? said: "In our survey, many of the positive comments about Southeastern were about its new high-speed trains, although these are only used on a handful of its routes. Other respondents mentioned cuts to other services, while overcrowding, high fares in relation to service and cancellations were recurrent themes. One (respondent) told us her husband's train is cancelled 'three to four times a week'."