They launched an inquiry amid claims Wales was underfunded to the tune of hundreds of millions of pounds.
Chair Jocelyn Davies said they welcomed the promised funding floor of at least 15% more cash per head than England.
But she called for an agreement on block grants based on needs before the funding floor promise expires in 2020.
"The issue of funding for Wales has been a bone of contention since the establishment of the now long-since discredited Barnett Formula," said Ms Davies.
"An agreement over a funding floor between the UK and Welsh governments is a positive step, but that deal expires in 2020.
"We think it is critical that any agreement around funding for Wales is put at the top of the agenda."
Economist Gerald Holtham, who advised the committee, said "some things have not changed" since he chaired an inquiry which reported in 2009 that Wales was underfunded by Â£300m a year.
"We called for a needs-based formula for Wales then, and these calls are being repeated six years later in this report," he said.
The report also called for an independent body to set the block grants and settle disputes between the UK Treasury and the devolved governments.
The UK Treasury has been asked to comment.
Fair funding for Wales by the UK Treasury should be guaranteed by law before tax powers are devolved, AMs on the finance committee have said.