I thought i would throw in my experiences here!
I have been to the soho store a few times and general try to get out of there as quick as possible as i like to spend time to decide on products i want to buy (otherwise i would buy the whole shop) and It seems once i have got a MA's attention and get one thing as i'm abou tto ask for the next they say oh i'll leave this behind the till and run off to someone else...always feel so very rushed in there. Fair play they are usually busy as they are a pro store. but i will only go there if i really need something!
Covent garden i havent been to before but a friend has and after the way they spoke to her i don't plan on going there. she went in to buy a technakohl liner. Once she got the MA's attention and asked for the liner the MA said well this isn't very good but if you want it for the water line you should use this and this liner is also much better. my friend had litterally nipped in there for just this liner as she has used it before and they MA was making it plain difficult for her even after she explained she has used it, didn't want it for her waterline and was in a rush! She also heard 2 MA's taking the P**s out of a customers make up - personally i would hate to think that MA's were taking the mick out of me.
Brent Cross Fenwicks - i used to go there a lot and will pop by from time time if im at the shopping centre but i will never go out of my way to go there or ask for advice. I went in to ask about foundations and concealers when i was fairly new to mac and the MA just told me to pick which one i thought. and when i picked she went yes! but it wasn't in way that she was trying to help - it was like she couldn't be bothered - i ended up spending near on £200 that day and all she seemed to do when i asked for something else was tut!!!!
Selfridges - 2 words! NEVER AGAIN! i went in not even needing advice just to see if 2 things were in stock! the MA simply dumped them in my hand and said take them to the till when your ready!
Now for my fav counter that has hardly had a mention and thats House of Fraser in the City. the MA's know me by name, they take their time to help me out and advise me on new collections and tells me how different products work if im not familiar with them. Take time to have a chat for example, just before summer i popped in to get a mineralize skinfinish duo, I told the MA that i was going on hols in a week so needed it for when i was tanned and she picked out the best colour for me after asking how easily i tanned etc etc. I didn't go in there until Mid September and when i came in she asked me how my holiday was and even remembered where i went! now thats what i call customer service! There is usually one MA that comes straight too me but if she isn't there all of the girls have helped me at some stage and have always been so helpful! try to avoid before 9am, between 12pm - 1pm and 5pm - 6pm! thankfully this fits around my working hours
hope that helps