As someone who has lived in London or the South East (Chilterns and SWML country) for 2/3rds of my life and the Northwest for the other 1/3rd, I utterly disagree with PR1s predictably tedious gravel-for-breakfast comment.
I found trains in the NW were much better at being direct, or with just 1 change, to get to the places I wanted (Scotland, other NW cities, NE, London, Midlands, South Coast).
In comparison, I think the South/London is great if you're going to London or happen to live on or near the radial line that goes to your destination elsewhere. If you miss that 1 in 11 chance (BML, SWML, GWML, CML, WCML, MML, ECML, WAML, GEML, HS1, SEML which probably isnt all !) then you are pretty stuffed, and almost always require a doubling of cost, time and stress to go into &/or cross London and come out again.
Typically I need 2 or 3 changes of trains to get places (Anglia, South West, Bristol/S.Wales, North West, East Midlands).
I was going to write frequency is better in the South, but then actually thought about it and questioned that - long journeys are always planned in advance so waiting at the outset is rare (and hence why it is/feels longer in the South due to more interchanges where you can't avoid waiting), and short distances (eg within NW or commuting into London has always felt like a 10/15/20max waiting time on a random turn-up-and go basis anyway.
For London and particulalry SW/West of it I'd like to see more development of orbital routes, or at least interchanges where radial routes do overlap (thinking West Hampstead...).
The East-West Rail Link seems a bit too far out, and doesn't link anything north of the GWML to anything south of it any better.