In regards to the recent mention of choice on the London to Birmingham route- I will do my best to explain what the choice is for people travelling to or from Milton Keynes- to London and to Birmingham. I think that the variety of choices and tickets can benefit passengers from here- as long as they can get their head around what is on offer.
From Milton Keynes, Virgin prices actually compare favourably to London Midland. (All prices quoted are with Y-P discount, as that is what I am familiar with).
Getting to London- 3 TOCs to choose from. London Midland and Virgin to Euston, Southern to the West London Line.
Advantages for London Midland
-Offer advance fares from £3.30.
-Have the first departures there and the last departures back. (0330 is also considered valid on off peak, and they have the earliest off peak arrival at Euston after 1000)
-Have an hourly 110mph service that is only slightly slower than VT
-Have the cheapest day travelcard option- £12.85 for an Off Peak Z1-6 travelcard. The cost of this ticket actually was reduced in the last fare 'increase', I don't doubt this is a move to get more people onto LM! Still, for me it means cheaper London trips.
-Don't have any set down/pick up only services at Milton Keynes
Disadvantages of London Midland
-Slower journey times, most services stop at intermediate stations
-Trains may not be considered as comfortable (350/2s especially)
-Poor first class offering
-Fast services are usually rammed
-More expensive in peak times, no London Midland Only anytime tickets available
Advantages of Virgin Trains
-Fastest, non stop service, 3 times an hour
-More capacity on most trains
-Better first class service
-Only 35p more expensive on a day travelcard ticket
-Same price as London Midland Only for off peak singles/returns
-Offer cheaper Virgin Trains Only anytime tickets for travel in peak times
Disadvantages of Virgin Trains
-All 3 London Services depart within 16 minutes of the hour
-Have a great chunk of the day when no services serve between Milton Keynes and London (although may stop for travel to/from the north), making the usefulness of the Virgin Trains Only anytime fare limited
-No Advance fare offering
-Later first train to London and earlier last train from London
-Late night services timetabled to take just as long as London Midland- 2230/2330 departures take an hour to get to MK (though in practice often arrive at MK very early)
Advantages of Southern
-First off peak departure after 0900 from Milton Keynes
-Offers a different range of destinations, which may be more convenient
Disadvantages of Southern
-Least frequent service at 1tph
-Slow service
-Earliest last journey back- ridiculously early on Saturdays. (From Olympia- Weekdays 2050 Saturdays 1750), which has always been too early for my needs.
-Southern Only Travelcard is no cheaper than Virgin, and more expensive than London Midland.
-During disruption, service is often pulled completely.
For Birmingham, the situation is different. Virgin again offer the quicker service, this time, always much quicker. This time though, Virgin offer advance fares which undercut the London Midland advance fares- VT from £2.30 and LM from £3.30. Virgin also offer the odd SVH fare which undercuts even the Super Off Peak London Midland Only single fare. Walk up though, London Midland are cheaper, as Virgin don't (Can't?) offer Virgin Trains Only fares. However, for railcard users, Virgin are definitely cheaper for walk up fares in peak times, as they will accept off peak railcard discounted tickets thanks to their easement. Unfortunately this doesn't apply for journeys between MK and Euston.
In terms of service provision, London Midland offer 2tph, but one is overtaken, and the other doesn't leave much after the VT service, and doesn't get in much before the next one! LM however do offer the earliest service there and the latest service back. (Not true if doing the opposite journey- first train from BHM is VT as is the last service back!)
So, living where I do, it is a myth that Virgin are always more expensive. In fact, they are often cheaper or the same price as the competition.
In the future, MK will probably have a fourth option to get to London- a Chiltern service from MK to Marylebone, we shall see what the fares comparison looks like then!