Always avoid LHR now
I travel regularly from Hong Kong and either use LGW and Oasis (LoCo but use ex BA crew ostracised by the 'useless at 55' rule) so flight is great, HK departure is a dream, especially for us HKID holders, we just use a card swip and thumb print to get in and out so no obergroebenfuhrers to get by, LGW is the only bad part, but early arrivals are usual trouble free.
Alternate is AF to CDG and transfer to EGHI, I live on the IOW, travel time is the same as a direct from LHR, despite changing as you have to leave sooo much time to get to and then through LHR. Price is the same and the food is better.
For any other parts of the world, go from exeter/bristol to amsterdam or shannon and then on, cost is minimal and the stress levels are v low.
BA are loosing vast amounts of revenue from LHR, but its not just BAA that are the problem, the whole area infrastructure (air and land) are creaking, close to collapse and a glossy new terminal and tower will not allow anyone to get in and out of LHR any faster.
KEEP CLEAR