Bit late to this thread so, for what they are worth, are my observations.
Until i moved to MK for work this summer I was a regular traveller from Darlington/Northallerton to all points on the ECML. I have been using the service, both first and second class, for at least 20 years on my own and for most of my life before that (we didn’t have a car for a long time!)
BR/Intercity = Offered a great train service, which , at times ,fell short on customer service. However compared to what we get on many routes now it was first class and cost us as tax players very little. The service was profitable, quick, punctual. It was an improving service which GNER rightly spotted as the jewel in the crown and paid big to get hold of.
They took the framework Intercity put in place, staff, trains, routes, service and built on that. Customer service was always excellent, food was excellent, first class was simply wonderful, second class was good too. They ran a proper train service and made train travel exciting and attractive. I often travelled for business first class and they had targeted offers, loyalty cards and never tried to undercut the cheaper options. They had a premium service, knew this and ran it accordingly. They overbid to keep the franchise and paid for it, as did we the travelling public.
National Express tried to destroy all of the BR/GNER good work. The quality of service feel through the floor, staff were main redundant, facilities run down. They ran a premium intercity service like one of their bloody buses. God only knows what it would have been like if they carried on. They reduced a premium service and increased the price. Staff morale was terrible, staff numbers were down and they introduced ticket barriers (luckily they were beaten at York!) The reliability of the trains, always a priority before fell, as did on board standards. They were a disaster and should have been stripped of all their franchises.
East Coast are trying hard to reverse the decline. There is a template to follow, just follow it. They have started to climb back up the hill but I doubt anyone will reach the standards set by GNER. At least they seem to understand that trains are not busses and that passengers dont want to be squashed into cattle trucks. The trains are cleaner and are being delivered, reliability is coming back up and the timetable is pretty decent but could do with some polishing.
So league table:
1) GNER
2) BR/Intercity
3) East Coast
4) By a long way NEX