'Stark' difference in rail service in Wales and Scotland
Train services in Wales are lagging behind others in the UK and could be improved by devolving responsibility, says a report.
The study for the Campaign for Better Transport shows services are used less and have lower passenger satisfaction.
The Welsh government said it cannot comment on research it has not seen.
It comes as details of a £24m upgrade in rail stations at Rhyl, Aberystwyth, Pontypridd, Port Talbot Parkway and Ystrad Mynach was revealed.
Stephen Joseph, the chief executive of the transport charity said the devolved Scottish rail service faired better than the one in Wales which is managed by Whitehall.
"There is definitely room for improvement and a case for the Welsh government to make the case for much more control over the Welsh railway... and managing it much more itself," he told BBC Radio Wales.
Earlier this year it emerged the Department for Transport has been in discussion with the Welsh government to assess the feasibility of devolving responsibilities for the rail franchise held until 2018 by Arriva Trains Wales.
The report for the Campaign for Better Transport said in Wales, "rail has not established itself as a leading mode of travel", adding that along with the north east and the east of England the nation had the "greatest opportunities to improve rail services".
The research compares regional rail performance across investment, growth and passenger satisfaction.
Meanwhile, more details of investment in the five Welsh rail stations, including £17m from the European Regional Development Fund (ERDF), have been revealed by Transport Minister Edwina Hart.
The money will be used to improve customer facilities, access, capacity and park and ride spaces.
The report found networks in London, the north west and the west Midlands performed better while Wales, the north east and the east of England were at the other end of the scale.
Consultants Credo looked at areas like how many people used services, their quality, and how accessible they were.
Credo director Matt Lovering said: "The comparison between Scotland and Wales is stark, with devolved management of services in Scotland delivering significantly better results than the equivalent in Wales."
A spokesperson for the Rail Delivery Group, which speaks for the industry, said: "While there is always room for improvement, rail passengers are travelling on services that are unrecognisably better when compared to 15 years ago.
"Passenger satisfaction is at a near record high with 500 million more journeys each year being rated 'good' or 'satisfactory' according to the independent passenger watchdog."
Speaking in Port Talbot about the investment there and at four other Welsh stations, Mrs Hart said:
"I think when you see the station you can understand what refurbishment it needs, better disabled access and better parking," said Mrs Hart.
"It's a station that is used quite a lot by people from west Wales who come down to Port Talbot Parkway and then get on the train and get on with their business," said the transport minister Edwina Hart.
She said extra park and ride spaces were an important part of the strategy to reduce reliance on the car for people to get to work or go shopping.
The Welsh government is contributing £5.1m with £700,000 from Network Rail, and £400,000 from Arriva Trains Wales.
Neath Port Talbot council is paying £500,000 towards the Port Talbot Parkway scheme with steel for the project donated by Tata.