I flew to LHR to Nice last week - first BA flight for some time and it was OK. CC were reasonably professional, friendly...but for some, while the smile said one thing the body language was saying something else.
That said, I have always found the Gatwick crews (LH and SH) warmer and more enthuiastic.
Best of all, in my experience, were the CC of the BA francises. The GB crew at Gatwick were brilliant and the Maersk crews at Birmingham even better.
Worst experience was on a flight to Mauritius 3/4 years back which got of to a bad start at the gate. A member of ground staff (complete b*sta*d), kicked off. We were called to the gate before he and his accomplices had chance to set up the desk for F and Club - He rudely told the first few who got there and were waiting to board that they were at the wrong desk and to get to the back of the WT queue. A Mauritian guy smiled and explained that the desk had not been signposted so no one knew. Our BA friend snatched his boarding pass and SHOUTED that he wasn't being allowed to board. The Ba***rd) then proceeded to do the same to the next passenger who intervened and objected.
A great start to a holiday (not) that leaves a nasty taste to this day. It didn't improve en route when the CSD (?) started throwing her weight around - didn't stop her grabbing a hug with an Irish boy band celebrity passenger as we disembarked the following morning.
I seem to recall (from the now closed BA Industrial Relations thread) that MRS was not CCs favourite gig. It showed.