Just looked into getting a British Airways flight from MAN-LHR and I'd get into LHR at 8:10 on that. Not sure if I'd be able to link that ticket with my American ticket so I'm protected in the event of a delay. Not sure what's the best option at this point. If I fly down there's a chance it's delayed (train could be delayed to but I'd guess it's more likely the flight would be) and I'd be able to check my luggage all the way to LAX so I could just make the walk to Terminal 3 for my American flight. If I end up doing the train I'd definitely take the taxi to be safe even though it looks like the Virgin train, tube, and heathrow express would all be on one ticket so that would save some time.

I've got no preference for either as the cost is similar but not sure what everyone thinks in regards to which might be the safer bet? Thanks for the insight everyone.