I did this commute weekl/twice weekly regularly for about a year, now every six weeks or so for leisure.

Personally for work I preferred LHR, mainly because it was closer to home, and after a weekly commute that was more important to me than the use of the excellent LGW Terraces on the standard UK Business flex fare, though if you made Gold, the F lounge is nice in LGW, probably countered by the crappy 737s in the LGW fleet.

LGW anecdotally had fewer overall holding/taxiing/gate allocation delays, but it's all much of a muchness as any weather problems can really be a problem, especially early in the am with fog in winter on the single LGW runway.

Now I am Gold it's exLGW as it's easier to get to from the City on Frday afternoons, and I get the F lounge, and then I return into LHR for a quick and cheap hop on the tube back home Sunday evening.

You should certainly invest in a BAA Worldcard credit card (you have to phone them for this) and that get you a free upgrade to FIRST on the LGW/LHR Express Trains. In turn travelling first usually gives you a Fast Track voucher (just ask the person who checks your ticket).

So in short, try both and determine which suits you best, but personally without Gold status my bias would lean marginally towards LHR.

You should also be aware of this offer:

http://www.planerelief.com/default.aspx?src=home

Save yourself the pain of the plane. If you are planning on travelling by air between London & Manchester, Liverpool or Glasgow in April or May, keep your used boarding card and we'll swap it for a FREE First Class Virgin Trains' ticket. That's it. No catch. Simple and stress-free, the way travel should be.

Haven't taken the train to MAN since about 1998, when I lost patience with all the trackworks and defected to the plane and car, so will report back once I have redeemed my free ticket in late June.