Value for money
Whilst making comparisons with Heathrow it would only be fair to compare also the fees levied. If the airlines, and ultimately their passengers, are willing to pay airport charges in the order of Heathrow's £33-£42 per departing passenger then we might expect to see equivalent terminal and airside infrastructure. As it stands Manchester's charges are 20% to, at most, 35% of those, and that is before Heathrow reviews its charges to fund the development of Runway 3 (if it goes ahead).
Both airport's schedule of fees and charges are openly available on the internet.