As a Southern man I'm more than content with the three main railways south of the river, particularly the Brighton, to have a strong enough opinion on whether I prefer the East or West Coast. For some reason, my favourite north of the river mainline has always been the Great Eastern, I just wish it was a bit longer and stretched all the way to Great Yarmouth or Cromer.
The West Coast would be more interesting if it went via the M40 corridor. I find the Euston to Rugby section extremely boring. Probably the lack of junctions and inner suburban services turn me off. That said, I've had a closer relationship with the LMS than the LNER, considering I had a Duchess of Buccleuch 00 gauge local when I was a child with a lovely rake of LMS coaches.